diff --git a/paddlespeech/cli/asr/infer.py b/paddlespeech/cli/asr/infer.py
index c9ec058cd..6ae038539 100644
--- a/paddlespeech/cli/asr/infer.py
+++ b/paddlespeech/cli/asr/infer.py
@@ -119,8 +119,8 @@ class ASRExecutor(BaseExecutor):
                         lang: str='zh',
                         sample_rate: int=16000,
                         cfg_path: Optional[os.PathLike]=None,
-                        ckpt_path: Optional[os.PathLike]=None,
-                        device: str='cpu'):
+                        ckpt_path: Optional[os.PathLike]=None
+                        ):
         """
             Init model and other resources from a specific path.
         """
@@ -142,7 +142,6 @@ class ASRExecutor(BaseExecutor):
                 os.path.dirname(os.path.abspath(self.cfg_path)))
 
         #Init body.
-        paddle.set_device(device)
         self.config = CfgNode(new_allowed=True)
         self.config.merge_from_file(self.cfg_path)
         self.config.decoding.decoding_method = "attention_rescoring"
@@ -397,8 +396,8 @@ class ASRExecutor(BaseExecutor):
         """
         audio_file = os.path.abspath(audio_file)
         self._check(audio_file, sample_rate)
-        self._init_from_path(model, lang, sample_rate, config, ckpt_path,
-                             device)
+        paddle.set_device(device)
+        self._init_from_path(model, lang, sample_rate, config, ckpt_path)
         self.preprocess(model, audio_file)
         self.infer(model)
         res = self.postprocess()  # Retrieve result of asr.
diff --git a/paddlespeech/cli/executor.py b/paddlespeech/cli/executor.py
index c132b3b87..00371371d 100644
--- a/paddlespeech/cli/executor.py
+++ b/paddlespeech/cli/executor.py
@@ -14,6 +14,7 @@
 import os
 from abc import ABC
 from abc import abstractmethod
+from typing import Any
 from typing import List
 from typing import Union
 
@@ -32,50 +33,70 @@ class BaseExecutor(ABC):
     @abstractmethod
     def _get_pretrained_path(self, tag: str) -> os.PathLike:
         """
-            Download and returns pretrained resources path of current task.
+        Download and returns pretrained resources path of current task.
+
+        Args:
+            tag (str): A tag of pretrained model.
+
+        Returns:
+            os.PathLike: The path on which resources of pretrained model locate. 
         """
         pass
 
     @abstractmethod
     def _init_from_path(self, *args, **kwargs):
         """
-            Init model and other resources from a specific path.
+        Init model and other resources from arguments. This method should be called by `__call__()`.
         """
         pass
 
     @abstractmethod
-    def preprocess(self, input: Union[str, os.PathLike]):
+    def preprocess(self, input: Any, *args, **kwargs):
         """
-            Input preprocess and return paddle.Tensor stored in self.input.
-            Input content can be a text(tts), a file(asr, cls) or a streaming(not supported yet).
+        Input preprocess and return paddle.Tensor stored in self._inputs.
+        Input content can be a text(tts), a file(asr, cls), a stream(not supported yet) or anything needed.
+
+        Args:
+            input (Any): Input text/file/stream or other content.
         """
         pass
 
     @paddle.no_grad()
     @abstractmethod
-    def infer(self, device: str):
+    def infer(self, *args, **kwargs):
         """
-            Model inference and result stored in self.output.
+        Model inference and put results into self._outputs.
+        This method get input tensors from self._inputs, and write output tensors into self._outputs.
         """
         pass
 
     @abstractmethod
-    def postprocess(self) -> Union[str, os.PathLike]:
+    def postprocess(self, *args, **kwargs) -> Union[str, os.PathLike]:
         """
-            Output postprocess and return human-readable results such as texts and audio files.
+        Output postprocess and return results.
+        This method get model output from self._outputs and convert it into human-readable results.
+
+        Returns:
+            Union[str, os.PathLike]: Human-readable results such as texts and audio files.
         """
         pass
 
     @abstractmethod
     def execute(self, argv: List[str]) -> bool:
         """
-            Command line entry.
+        Command line entry. This method can only be accessed by a command line such as `paddlespeech asr`.
+
+        Args:
+            argv (List[str]): Arguments from command line.
+
+        Returns:
+            int: Result of the command execution. `True` for a success and `False` for a failure.
         """
         pass
 
     @abstractmethod
     def __call__(self, *arg, **kwargs):
         """
-            Python API to call an executor.
+        Python API to call an executor.
         """
         pass