diff --git a/paddle_quantum/circuit.py b/paddle_quantum/circuit.py
index 2eba39f84a900b6294c97dc01585ec2e47ebadae..4e5c6276f4fdbe31a8246c12ed8ca51747398371 100644
--- a/paddle_quantum/circuit.py
+++ b/paddle_quantum/circuit.py
@@ -26,7 +26,7 @@ from paddle import imag, real, reshape, kron, matmul, trace
 from paddle_quantum.utils import partial_trace, dagger, pauli_str_to_matrix
 from paddle_quantum import shadow
 from paddle_quantum.intrinsic import *
-from paddle_quantum.state import density_op
+from paddle_quantum.state import density_op,vec
 
 __all__ = [
     "UAnsatz",
@@ -59,7 +59,30 @@ class UAnsatz:
                         paddle.to_tensor(np.array([math.pi / 4])), paddle.to_tensor(np.array([-math.pi / 4]))]
         # Record history of adding gates to the circuit
         self.__history = []
-
+        
+    def expand(self,new_n):
+        """
+        为原来的量子电路进行比特数扩展
+
+        Args：
+            new_n(int):扩展后的量子比特数
+        """
+        assert new_n>=self.n,'扩展后量子比特数要大于原量子比特数'
+        diff = new_n-self.n
+        dim = 2**diff
+        if self.__state is not None:
+            if self.__run_mode=='density_matrix':
+                shape = (dim,dim)
+                _state = paddle.to_tensor(density_op(diff))
+            elif self.__run_mode=='state_vector':
+                shape = (dim,)
+                _state = paddle.to_tensor(vec(0,diff))
+            
+            _state= paddle.reshape(_state,shape)
+            _state = kron(self.__state,_state)
+            self.__state = _state
+        self.n = new_n
+        
     def __add__(self, cir):
         r"""重载加法 ‘+’ 运算符，用于拼接两个维度相同的电路
 
diff --git a/test_and_documents/readme.md b/test_and_documents/readme.md
new file mode 100644
index 0000000000000000000000000000000000000000..f8d685c16e9c38d7a45549471b137d378b5a50cc
--- /dev/null
+++ b/test_and_documents/readme.md
@@ -0,0 +1 @@
+通过在UAnsatz类中添加新的成员函数expand来实现扩展
diff --git a/test_and_documents/test.py b/test_and_documents/test.py
new file mode 100644
index 0000000000000000000000000000000000000000..9d998d8fcc7d6b1051c73bb1338a68f7c50de3c4
--- /dev/null
+++ b/test_and_documents/test.py
@@ -0,0 +1,34 @@
+from paddle_quantum.circuit import UAnsatz
+from paddle import kron
+from paddle_quantum.state import vec,density_op
+import paddle
+
+
+#density_matrix
+def test_density_matrix():
+    cir = UAnsatz(1)
+    cir.ry(paddle.to_tensor(1,dtype='float64'),0)
+    state = cir.run_density_matrix()
+    cir.expand(3)
+    print(cir.get_state())
+
+    cir2 = UAnsatz(3)
+    cir2.ry(paddle.to_tensor(1,dtype='float64'),0)
+    cir2.run_density_matrix()
+    print(cir2.get_state())
+
+#state_vector
+def test_state_vector():
+    cir = UAnsatz(1)
+    cir.ry(paddle.to_tensor(1,dtype='float64'),0)
+    state = cir.run_state_vector()
+    cir.expand(3)
+    print(cir.get_state())
+
+    cir2 = UAnsatz(3)
+    cir2.ry(paddle.to_tensor(1,dtype='float64'),0)
+    cir2.run_state_vector()
+    print(cir2.get_state())
+
+test_density_matrix()
+test_state_vector()