diff --git a/tianshou/utils/net/common.py b/tianshou/utils/net/common.py
index 7603454..5886912 100644
--- a/tianshou/utils/net/common.py
+++ b/tianshou/utils/net/common.py
@@ -604,3 +604,7 @@ class BaseActor(nn.Module, ABC):
     @abstractmethod
     def get_preprocess_net(self) -> nn.Module:
         pass
+
+    @abstractmethod
+    def get_output_dim(self) -> int:
+        pass
diff --git a/tianshou/utils/net/continuous.py b/tianshou/utils/net/continuous.py
index c69c249..60c3569 100644
--- a/tianshou/utils/net/continuous.py
+++ b/tianshou/utils/net/continuous.py
@@ -63,6 +63,9 @@ class Actor(BaseActor):
     def get_preprocess_net(self) -> nn.Module:
         return self.preprocess
 
+    def get_output_dim(self) -> int:
+        return self.output_dim
+
     def forward(
         self,
         obs: np.ndarray | torch.Tensor,
@@ -213,6 +216,9 @@ class ActorProb(BaseActor):
     def get_preprocess_net(self) -> nn.Module:
         return self.preprocess
 
+    def get_output_dim(self):
+        return self.output_dim
+
     def forward(
         self,
         obs: np.ndarray | torch.Tensor,
diff --git a/tianshou/utils/net/discrete.py b/tianshou/utils/net/discrete.py
index 083cac5..ccdd69d 100644
--- a/tianshou/utils/net/discrete.py
+++ b/tianshou/utils/net/discrete.py
@@ -64,6 +64,9 @@ class Actor(BaseActor):
     def get_preprocess_net(self) -> nn.Module:
         return self.preprocess
 
+    def get_output_dim(self) -> int:
+        return self.output_dim
+
     def forward(
         self,
         obs: np.ndarray | torch.Tensor,