diff --git a/mindquantum/core/operators/hamiltonian.py b/mindquantum/core/operators/hamiltonian.py
index 6de75ff86472f05219b063f6f29bd6210e4e75ad..b2204bef8808b06099c2cebb353614f82c269650 100644
--- a/mindquantum/core/operators/hamiltonian.py
+++ b/mindquantum/core/operators/hamiltonian.py
@@ -105,6 +105,25 @@ class Hamiltonian:
             return self.sparse_mat.__str__()
         return self.hamiltonian.__repr__()
 
+    def __getstate__(self):
+        """Create a dictionary that will be pickled."""
+        state = self.__dict__.copy()
+        # Remove the unpicklable entries.
+        if self.ham_cpp:
+            state['ham_cpp'] = True
+        if self.herm_ham_cpp:
+            state['herm_ham_cpp'] = True
+        return state
+
+    def __setstate__(self, state):
+        """Restore instance state from the unpickled state."""
+        self.__dict__.update(state)
+        # Add the missing 'ham_cpp' and 'herm_ham_cpp' entries
+        if self.ham_cpp:
+            self.ham_cpp = self.get_cpp_obj(hermitian=False)
+        if self.herm_ham_cpp:
+            self.herm_ham_cpp = self.get_cpp_obj(hermitian=True)
+
     def sparse(self, n_qubits=1):
         """
         Calculate the sparse matrix of this hamiltonian in pqc operator.
diff --git a/mindquantum/simulator/available_simulator.py b/mindquantum/simulator/available_simulator.py
index 493a8fb85e855dc5e041a5967635e51428aeae18..b5551e0e412e4bc73b4588e150d22acec3036f92 100644
--- a/mindquantum/simulator/available_simulator.py
+++ b/mindquantum/simulator/available_simulator.py
@@ -28,7 +28,11 @@ try:
     _mq_vector_gpu.double.mqvector_gpu(1).apply_gate(mqbackend.gate.HGate([0]))
     MQVECTOR_GPU_SUPPORTED = True
 except ImportError as err:
-    warnings.warn(f"Unable import mqvector gpu backend due to: {err}", stacklevel=2)
+    warnings.warn(
+        f"Unable import mqvector gpu backend. This could be due to your environment "
+        "not satisfying the requirements for mqvector_gpu, or the _mq_vector_gpu library may be missing.",
+        stacklevel=2,
+    )
     MQVECTOR_GPU_SUPPORTED = False
 except RuntimeError as err:
     warnings.warn(f"Disable mqvector gpu backend due to: {err}", stacklevel=2)
diff --git a/mindquantum/simulator/mqsim.py b/mindquantum/simulator/mqsim.py
index 8a7aae53451495074b419b1a1cb1a28c49dbb215..9cc13e18def5f61dec8f2bfc1ce6e7ae804cfb79 100644
--- a/mindquantum/simulator/mqsim.py
+++ b/mindquantum/simulator/mqsim.py
@@ -52,11 +52,13 @@ class MQSim(BackendBase):
     def __init__(self, name: str, n_qubits: int, seed=None, dtype=complex128, internal=False):
         """Initialize a mindquantum backend."""
         super().__init__(name, n_qubits, seed, dtype)
+        self.internal = internal
         if internal:
             self.sim = name
         else:
             if dtype is None:
                 dtype = complex128
+                self.arithmetic_type = dtype
             _check_mq_type(dtype)
             self.sim = getattr(SUPPORTED_SIMULATOR.c_module(name, dtype), name)(n_qubits, seed)
 
@@ -77,6 +79,22 @@ class MQSim(BackendBase):
         """Return a string representation of the object."""
         return self.__str__()
 
+    def __getstate__(self):
+        state = self.__dict__.copy()
+        # Remove the unpicklable entries.
+        del state['sim']
+        return state
+
+    def __setstate__(self, state):
+        self.__dict__.update(state)
+        # Restore the sim object
+        if self.internal:
+            self.sim = self.name
+        else:
+            self.sim = getattr(SUPPORTED_SIMULATOR.c_module(self.name, self.arithmetic_type), self.name)(
+                self.n_qubits, self.seed
+            )
+
     def apply_circuit(
         self,
         circuit: Circuit,