diff --git a/fedlab/contrib/algorithm/qfedavg.py b/fedlab/contrib/algorithm/qfedavg.py
index 1f9c9e4a..0c33ced3 100644
--- a/fedlab/contrib/algorithm/qfedavg.py
+++ b/fedlab/contrib/algorithm/qfedavg.py
@@ -2,6 +2,7 @@
 
 from .basic_server import SyncServerHandler
 from .basic_client import SGDClientTrainer
+from .basic_client import SGDSerialClientTrainer
 
 
 ##################
@@ -40,7 +41,7 @@ def uplink_package(self):
     def setup_optim(self, epochs, batch_size, lr, q):
         super().setup_optim(epochs, batch_size, lr)
         self.q = q
-    
+
     def train(self, model_parameters, train_loader) -> None:
         """Client trains its local model on local dataset.
         Args:
@@ -72,11 +73,12 @@ def train(self, model_parameters, train_loader) -> None:
             ret_loss + 1e-10, self.q - 1) * grad.norm(
             )**2 + 1.0 / self.lr * np.float_power(ret_loss + 1e-10, self.q)
 
+
 class qFedAvgSerialClientTrainer(SGDSerialClientTrainer):
     def setup_optim(self, epochs, batch_size, lr, q):
         super().setup_optim(epochs, batch_size, lr)
         self.q = q
-    
+
     def train(self, model_parameters, train_loader) -> None:
         """Client trains its local model on local dataset.
         Args: