diff --git a/torchquantum/algorithm/qcbm.py b/torchquantum/algorithm/qcbm.py
index 12a63dfb..fdd5a416 100644
--- a/torchquantum/algorithm/qcbm.py
+++ b/torchquantum/algorithm/qcbm.py
@@ -47,7 +47,7 @@ def forward(self, px, py):
         Squared MMD loss.
     Args:
             px: First probability distribution
-        py: Second probability distribution
+            py: Second probability distribution
 
         Returns:
             Squared MMD loss.