diff --git a/src/examples/bell_state/host.py b/src/examples/bell_state/host.py
index b1e72db16f3d3cdd6cff26443a895e65b2e542d3..c3fd7559db3245d8174c8b019e47b85a68649e3f 100644
--- a/src/examples/bell_state/host.py
+++ b/src/examples/bell_state/host.py
@@ -6,18 +6,18 @@ from pathlib import Path
 # qi.set_log_level(logging.DEBUG)
 qi.set_compiler('mlir')
 
-if qi.connect_backend('pyqcisim_quantumsim') is False:
+if qi.connect_backend('symqc_quantumsim') is False:
     exit(-1)
-
+ 
 qu_file = Path(__file__).parent / "kernel.qu"
 
 
 def routine(circ_name, num_shots=1):
-    qi.set_num_shots(num_shots)
+
     if not qi.call_quingo(qu_file, circ_name):
         print("Failed to call {}".format(circ_name))
     print("The result of {} is:".format(circ_name))
     print(qi.read_result())
 
 
-routine("bell_state", 1000)
+routine("bell_state")
diff --git a/src/quingo/if_backend/backend_hub.py b/src/quingo/if_backend/backend_hub.py
index ca9a59c12a57d50f164b482a1b9ebd9b769848c4..10c1ea3cb1aac6c09ddb1c0cb2725f81f6f1913b 100755
--- a/src/quingo/if_backend/backend_hub.py
+++ b/src/quingo/if_backend/backend_hub.py
@@ -3,8 +3,8 @@ import importlib
 
 class Backend_info():
     def __init__(self, module_name, module_path,  with_timing, is_simulator):
-        self.module_name = module_name
-        self.module_path = module_path
+        self.module_name = module_name   #库名字
+        self.module_path = module_path   #库路径
         self.with_timing = with_timing
         self.is_simulator = is_simulator
 
@@ -23,7 +23,8 @@ class Backend_info():
         return module
 
     def get_instance(self):
-        return getattr(self.get_module(), self.module_name)()
+        #从给定文件中拿出模块对应的名字
+        return getattr(self.get_module(), self.module_name)() 
 
 
 def singleton(cls):
@@ -37,7 +38,7 @@ def singleton(cls):
 
 
 @singleton
-class Backend_hub():
+class Backend_hub(): 
     def __init__(self):
         self.backends = {}
 
@@ -49,9 +50,13 @@ class Backend_hub():
             'PyQCISim_quantumsim', 'pyqcisim_quantumsim', with_timing=False,
             is_simulator=True)
 
+        self.backends['symqc_quantumsim'] = Backend_info(
+            'SymQC_quantumsim', 'symqc_quantumsim', with_timing=False,
+            is_simulator=True)
+
     def support(self, backend_name):
         return (backend_name in self.backends)
 
     def get_instance(self, backend_name):
         backend_info = self.backends[backend_name]
-        return backend_info.get_instance()
+        return backend_info.get_instance()   
diff --git a/src/quingo/if_backend/non_arch_backend/symqc_quantumsim.py b/src/quingo/if_backend/non_arch_backend/symqc_quantumsim.py
new file mode 100644
index 0000000000000000000000000000000000000000..d49f37f1e5a114cd554ff0cd851be8fd9df6ab26
--- /dev/null
+++ b/src/quingo/if_backend/non_arch_backend/symqc_quantumsim.py
@@ -0,0 +1,64 @@
+from pathlib import Path
+from quingo.if_backend.if_backend import If_backend
+import quingo.global_config as gc
+from quingo.core.utils import *
+from symqc import do_sim
+# from SymQC import do_sim;
+# from symqc.output.symbol_map import symbol_map
+
+
+logger = get_logger((__name__).split('.')[-1])
+
+
+class SymQC_quantumsim(If_backend):
+    """A functional QCIS simulation backend using PyQCISim and QuantumSim."""
+
+    def __init__(self, **kwargs):    #关键字参数
+        
+        super().__init__("SymQC_QuantumSim", is_simaultor=True)
+        self.sim = do_sim.SymQC()
+        self.pyqcisim_dir = gc.qgrtsys_root_dir / "if_backend" / "symqc"
+        self.verbose = kwargs.pop('verbose', False)  #没有就返回False
+        self.loglevel = kwargs.pop('loglevel', logging.INFO)   #没有就返回logging.INFO
+        logger.setLevel(self.loglevel)
+        self.res = None
+
+    def available(self):
+        return True
+
+    def get_qisa(self):
+        return "qcis"
+
+    def set_log_level(self, log_level):
+        self.log_level = log_level 
+        logger.setLevel(self.log_level) 
+
+    def set_verbose(self, verbose):
+        pass
+
+    def upload_program(self, prog_fn, is_binary=False):
+        assert not is_binary
+
+        if not isinstance(prog_fn, Path):
+             prog_fn = Path(prog_fn)
+
+        f = prog_fn.open('r').read()    #前面的都是读文件的操作，读入f
+        try:
+            #此处为compile过程
+            self.sim.compiler(f)
+            return True
+        except Exception as e:
+            quingo_err("Error in the QCIS program compiling process of PyQCISim: {}".format(e))
+            return False
+
+    def execute(self):
+        try:
+            self.res=self.sim.excute()
+            return True
+        except Exception as e:
+            quingo_err("Error in PyQCISim Simulation: {}".format(e))
+            return False
+
+    def read_result(self):    #这里承接manager.py
+        """This function tries to read the computation result of the quantum kernel."""
+        return self.res