diff --git a/packages/expression-engine/jest.config.js b/packages/expression-engine/jest.config.cjs
similarity index 100%
rename from packages/expression-engine/jest.config.js
rename to packages/expression-engine/jest.config.cjs
diff --git a/packages/expression-engine/lib/expression-engine/expression_engine.spec.ts b/packages/expression-engine/lib/expression-engine/expression_engine.spec.ts
index ae8183a11497177c2ca5f5def25a5ab507037787..ad06c292f1e9dca2d9e07f959847d43d218cfbee 100644
--- a/packages/expression-engine/lib/expression-engine/expression_engine.spec.ts
+++ b/packages/expression-engine/lib/expression-engine/expression_engine.spec.ts
@@ -139,7 +139,7 @@ describe('ExpressionEngine', () => {
         expect(service.eval("DefaultFunction.GetBirthday('370784199012037014')")).toBe('1990-12-03');
     });
     it('# GetAge', () => {
-        expect(service.eval("DefaultFunction.GetAge('370784192112037014')")).toBe(102);
+        expect(service.eval("DefaultFunction.GetAge('370784192112037014')")).toBe(103);
     });
     it('# DateTimeAddDays', () => {
         expect(service.eval("DefaultFunction.FormatDefineDate('yyyy-MM-dd HH:mm:ss',DefaultFunction.DateTimeAddDays('2020-01-01 00:00:00',1))")).toBe('2020-01-02 00:00:00');
@@ -257,6 +257,30 @@ describe('ExpressionEngine', () => {
     it('# GetFirstDayOfMonth', () => {
         expect(service.eval("DefaultFunction.GetFirstDayOfMonth('2020-01-23')")).toBe('2020-01-01');
     });
+    it('# FirstDayOfLastMonth1', () => {
+        expect(service.eval("DefaultFunction.FirstDayOfLastMonth('2025-01-23')")).toBe('2024-12-01');
+    });
+    it('# FirstDayOfLastMonth2', () => {
+        expect(service.eval("DefaultFunction.FirstDayOfLastMonth('2025-12-23')")).toBe('2025-11-01');
+    });
+    it('# LastDayOfLastMonth1', () => {
+        expect(service.eval("DefaultFunction.LastDayOfLastMonth('2025-01-23')")).toBe('2024-12-31');
+    });
+    it('# LastDayOfLastMonth2', () => {
+        expect(service.eval("DefaultFunction.LastDayOfLastMonth('2025-12-23')")).toBe('2025-11-30');
+    });
+    it('# FirstDayOfNextMonth1', () => {
+        expect(service.eval("DefaultFunction.FirstDayOfNextMonth('2025-01-23')")).toBe('2025-02-01');
+    });
+    it('# FirstDayOfNextMonth2', () => {
+        expect(service.eval("DefaultFunction.FirstDayOfNextMonth('2025-12-23')")).toBe('2026-01-01');
+    });
+    it('# LastDayOfNextMonth1', () => {
+        expect(service.eval("DefaultFunction.LastDayOfNextMonth('2025-01-23')")).toBe('2025-02-28');
+    });
+    it('# LastDayOfNextMonth2', () => {
+        expect(service.eval("DefaultFunction.LastDayOfNextMonth('2025-12-23')")).toBe('2026-01-31');
+    });
     it('# GetLastDayOfMonth', () => {
         expect(service.eval("DefaultFunction.GetLastDayOfMonth('2020-01-23')")).toBe('2020-01-31');
     });
@@ -322,7 +346,7 @@ describe('ExpressionEngine', () => {
         const context = service.getContext();
         const defaultFunction = new DefaultFunctions(context);
         console.log(defaultFunction.FormatDate('yyyy-MM-dd'));
-        expect(service.eval("DefaultFunction.FormatDate()")).toBe('2024-07-02');
+        expect(service.eval("DefaultFunction.FormatDate()")).toBe('2025-09-25');
     });
     // it('# GetDateTimeNow', () => {
     //     const context = service.getContext();
@@ -365,4 +389,88 @@ describe('ExpressionEngine', () => {
         expect(service.eval("DefaultFunction.DayDifference('2024-2-32 00:00:00', '2024-1-1 09:00:00')")).toBe(null);
         expect(service.eval("DefaultFunction.DayDifference('This is a date', '2024-1-1 09:00:00')")).toBe(null);
     });
+
+    // FirstDayOfLastMonth 测试用例
+    it('# FirstDayOfLastMonth - normal cases', () => {
+        expect(service.eval("DefaultFunction.FirstDayOfLastMonth('2025-01-23')")).toBe('2024-12-01');
+        expect(service.eval("DefaultFunction.FirstDayOfLastMonth('2025-12-23')")).toBe('2025-11-01');
+        expect(service.eval("DefaultFunction.FirstDayOfLastMonth('2025-06-15')")).toBe('2025-05-01');
+    });
+
+    it('# FirstDayOfLastMonth - invalid inputs', () => {
+        expect(service.eval("DefaultFunction.FirstDayOfLastMonth('')")).toBe('2025-08-01');
+        expect(service.eval("DefaultFunction.FirstDayOfLastMonth(null)")).toBe('2025-08-01');
+    });
+
+    // LastDayOfLastMonth 测试用例
+    it('# LastDayOfLastMonth - normal cases', () => {
+        expect(service.eval("DefaultFunction.LastDayOfLastMonth('2025-01-23')")).toBe('2024-12-31');
+        expect(service.eval("DefaultFunction.LastDayOfLastMonth('2025-12-23')")).toBe('2025-11-30');
+        expect(service.eval("DefaultFunction.LastDayOfLastMonth('2025-03-15')")).toBe('2025-02-28');
+    });
+
+    it('# LastDayOfLastMonth - leap year', () => {
+        expect(service.eval("DefaultFunction.LastDayOfLastMonth('2024-03-01')")).toBe('2024-02-29');
+        expect(service.eval("DefaultFunction.LastDayOfLastMonth('2100-03-01')")).toBe('2100-02-28'); // 世纪年
+    });
+
+    it('# LastDayOfLastMonth - invalid inputs', () => {
+        expect(service.eval("DefaultFunction.LastDayOfLastMonth('')")).toBe('2025-08-31');
+        expect(service.eval("DefaultFunction.LastDayOfLastMonth(null)")).toBe('2025-08-31');
+    });
+
+    // FirstDayOfNextMonth 测试用例
+    it('# FirstDayOfNextMonth - normal cases', () => {
+        expect(service.eval("DefaultFunction.FirstDayOfNextMonth('2025-01-23')")).toBe('2025-02-01');
+        expect(service.eval("DefaultFunction.FirstDayOfNextMonth('2025-12-23')")).toBe('2026-01-01');
+        expect(service.eval("DefaultFunction.FirstDayOfNextMonth('2025-06-30')")).toBe('2025-07-01');
+    });
+
+    it('# FirstDayOfNextMonth - different formats', () => {
+        expect(service.eval("DefaultFunction.FirstDayOfNextMonth('2025/01/23')")).toBe('2025-02-01');
+        expect(service.eval("DefaultFunction.FirstDayOfNextMonth('2025-1-23')")).toBe('2025-02-01');
+        expect(service.eval("DefaultFunction.FirstDayOfNextMonth('2025-01-23 15:30:00')")).toBe('2025-02-01');
+    });
+
+    it('# FirstDayOfNextMonth - invalid inputs', () => {
+        expect(service.eval("DefaultFunction.FirstDayOfNextMonth('')")).toBe('2025-10-01');
+        expect(service.eval("DefaultFunction.FirstDayOfNextMonth(undefined)")).toBe('2025-10-01');
+    });
+
+    // LastDayOfNextMonth 测试用例
+    it('# LastDayOfNextMonth - normal cases', () => {
+        expect(service.eval("DefaultFunction.LastDayOfNextMonth('2025-01-23')")).toBe('2025-02-28');
+        expect(service.eval("DefaultFunction.LastDayOfNextMonth('2025-12-23')")).toBe('2026-01-31');
+        expect(service.eval("DefaultFunction.LastDayOfNextMonth('2025-06-30')")).toBe('2025-07-31');
+    });
+
+    it('# LastDayOfNextMonth - special months', () => {
+        expect(service.eval("DefaultFunction.LastDayOfNextMonth('2024-01-31')")).toBe('2024-02-29'); // 闰年2月
+        expect(service.eval("DefaultFunction.LastDayOfNextMonth('2025-01-31')")).toBe('2025-02-28'); // 平年2月
+        expect(service.eval("DefaultFunction.LastDayOfNextMonth('2025-11-30')")).toBe('2025-12-31'); // 12月
+    });
+
+    it('# LastDayOfNextMonth - invalid inputs', () => {
+        expect(service.eval("DefaultFunction.LastDayOfNextMonth('')")).toBe('2025-10-31');
+        expect(service.eval("DefaultFunction.LastDayOfNextMonth(null)")).toBe('2025-10-31');
+    });
+
+    // GetLastDayOfMonth 测试用例
+    it('# GetLastDayOfMonth - normal cases', () => {
+        expect(service.eval("DefaultFunction.GetLastDayOfMonth('2020-01-23')")).toBe('2020-01-31');
+        expect(service.eval("DefaultFunction.GetLastDayOfMonth('2020-04-15')")).toBe('2020-04-30');
+        expect(service.eval("DefaultFunction.GetLastDayOfMonth('2020-02-01')")).toBe('2020-02-29');
+    });
+
+    it('# GetLastDayOfMonth - month variations', () => {
+        expect(service.eval("DefaultFunction.GetLastDayOfMonth('2021-02-15')")).toBe('2021-02-28'); // 平年2月
+        expect(service.eval("DefaultFunction.GetLastDayOfMonth('2024-02-15')")).toBe('2024-02-29'); // 闰年2月
+        expect(service.eval("DefaultFunction.GetLastDayOfMonth('2025-04-01')")).toBe('2025-04-30'); // 30天月份
+        expect(service.eval("DefaultFunction.GetLastDayOfMonth('2025-05-01')")).toBe('2025-05-31'); // 31天月份
+    });
+
+    it('# GetLastDayOfMonth - invalid inputs', () => {
+        expect(service.eval("DefaultFunction.GetLastDayOfMonth('')")).toBe('');
+        expect(service.eval("DefaultFunction.GetLastDayOfMonth(null)")).toBe(null);
+    });
 });
diff --git a/packages/expression-engine/lib/function/default_functions.ts b/packages/expression-engine/lib/function/default_functions.ts
index 5c79a1cc9a9fe201af1ef13bc8a568399830bb81..7dddcefed0cca67cfc8762159c2ad203377df18f 100644
--- a/packages/expression-engine/lib/function/default_functions.ts
+++ b/packages/expression-engine/lib/function/default_functions.ts
@@ -221,7 +221,7 @@ export class DefaultFunctions {
         const format = 'yyyy-MM-dd HH:mm:ss';
         start = this.FormatDefineDate(format, start);
         end = this.FormatDefineDate(format, end);
-        const condition = function (value: number, context: { isValidDate: (arg0: any) => any; FormatDefineDate: (arg0: string, arg1: any) => any }) {
+        const condition = function (value: number, context: { isValidDate: (arg0: any) => any; FormatDefineDate: (arg0: string, arg1: any) => any; }) {
             if (context.isValidDate(value)) {
                 value = context.FormatDefineDate(format, value);
             }
@@ -251,7 +251,7 @@ export class DefaultFunctions {
         const format = 'yyyy-MM-dd HH:mm:ss';
         start = this.FormatDefineDate(format, start);
         end = this.FormatDefineDate(format, end);
-        const condition = function (value: number, context: { isValidDate: (arg0: any) => any; FormatDefineDate: (arg0: string, arg1: any) => any }) {
+        const condition = function (value: number, context: { isValidDate: (arg0: any) => any; FormatDefineDate: (arg0: string, arg1: any) => any; }) {
             if (context.isValidDate(value)) {
                 value = context.FormatDefineDate(format, value);
             }
@@ -280,7 +280,7 @@ export class DefaultFunctions {
         const format = 'yyyy-MM-dd HH:mm:ss';
         start = this.FormatDefineDate(format, start);
         end = this.FormatDefineDate(format, end);
-        const condition = function (value: number, context: { isValidDate: (arg0: any) => any; FormatDefineDate: (arg0: string, arg1: any) => any }) {
+        const condition = function (value: number, context: { isValidDate: (arg0: any) => any; FormatDefineDate: (arg0: string, arg1: any) => any; }) {
             if (context.isValidDate(value)) {
                 value = context.FormatDefineDate(format, value);
             }
@@ -1370,47 +1370,37 @@ export class DefaultFunctions {
         if (!date) {
             const currentDate = new Date();
             const currentMonth = currentDate.getMonth();
-            // 获得当前年份4位年
             const currentYear = currentDate.getFullYear();
-            // 求出本月第一天
-            const firstDay = new Date(currentYear, currentMonth, 1);
-            firstDay.setMonth(firstDay.getMonth());
-            // 返回
-            return this.FormatDefineDate('yyyy-MM-dd', firstDay);
+            // 如果是1月份，需要处理年份
+            if (currentMonth === 0) {
+                return this.FormatDefineDate('yyyy-MM-dd', new Date(currentYear - 1, 11, 1));
+            }
+            // 其他月份
+            return this.FormatDefineDate('yyyy-MM-dd', new Date(currentYear, currentMonth - 1, 1));
         }
-
         const currentDate = new Date(date);
         const currentMonth = currentDate.getMonth();
-        // 获得当前年份4位年
         const currentYear = currentDate.getFullYear();
-        // 求出本月第一天
-        const firstDay = new Date(currentYear, currentMonth, 1);
-        firstDay.setMonth(firstDay.getMonth());
-        // 返回
-        return this.FormatDefineDate('yyyy-MM-dd', firstDay);
-
+        // 如果是1月份，需要处理年份
+        if (currentMonth === 0) {
+            return this.FormatDefineDate('yyyy-MM-dd', new Date(currentYear - 1, 11, 1));
+        }
+        // 其他月份
+        return this.FormatDefineDate('yyyy-MM-dd', new Date(currentYear, currentMonth - 1, 1));
     }
 
     // 上月最后一天
     public LastDayOfLastMonth(date = null) {
-        if (!date) {
-            const currentDate = new Date();
-            const fullYear = currentDate.getFullYear();
-            const month = currentDate.getMonth() + 1;
-            // getMonth 方法返回 0-11，代表1-12月
-            const endOfMonth = new Date(fullYear, month, 0);
-            endOfMonth.setMonth(endOfMonth.getMonth());
-            return this.FormatDefineDate('yyyy-MM-dd', endOfMonth);
+        let currentDate = new Date();
+        if (date) {
+            currentDate = new Date(date);
         }
-
-        const currentDate = new Date(date);
-        const fullYear = currentDate.getFullYear();
-        const month = currentDate.getMonth() + 1;
-        // getMonth 方法返回 0-11，代表1-12月
-        const endOfMonth = new Date(fullYear, month, 0);
-        endOfMonth.setMonth(endOfMonth.getMonth());
-        return this.FormatDefineDate('yyyy-MM-dd', endOfMonth);
-
+        // 获取上个月的最后一天
+        const year = currentDate.getFullYear();
+        const month = currentDate.getMonth(); // 当前月份，0-11
+        // 传入当前年份和当前月份，就能获取上个月的最后一天
+        const lastDayOfLastMonth = new Date(year, month, 0);
+        return this.FormatDefineDate('yyyy-MM-dd', lastDayOfLastMonth);
     }
     // 下月第一天