diff --git a/test/base/test_batch.py b/test/base/test_batch.py
index ab886dd..0d30a0a 100644
--- a/test/base/test_batch.py
+++ b/test/base/test_batch.py
@@ -11,7 +11,7 @@ def test_batch():
     assert batch.obs == batch["obs"]
     batch.obs = [1]
     assert batch.obs == [1]
-    batch.append(batch)
+    batch.cat(batch)
     assert batch.obs == [1, 1]
     assert batch.np.shape == (6, 4)
     assert batch[0].obs == batch[1].obs
@@ -34,13 +34,13 @@ def test_batch_over_batch():
     print(batch2)
     assert batch2.values()[-1] == batch2.c
     assert batch2[-1].b.b == 0
-    batch2.append(Batch(c=[6, 7, 8], b=batch))
+    batch2.cat(Batch(c=[6, 7, 8], b=batch))
     assert batch2.c == [6, 7, 8, 6, 7, 8]
     assert batch2.b.a == [3, 4, 5, 3, 4, 5]
     assert batch2.b.b == [4, 5, 0, 4, 5, 0]
     d = {'a': [3, 4, 5], 'b': [4, 5, 6]}
     batch3 = Batch(c=[6, 7, 8], b=d)
-    batch3.append(Batch(c=[6, 7, 8], b=d))
+    batch3.cat(Batch(c=[6, 7, 8], b=d))
     assert batch3.c == [6, 7, 8, 6, 7, 8]
     assert batch3.b.a == [3, 4, 5, 3, 4, 5]
     assert batch3.b.b == [4, 5, 6, 4, 5, 6]
diff --git a/tianshou/data/batch.py b/tianshou/data/batch.py
index 61d23d9..f6c1df6 100644
--- a/tianshou/data/batch.py
+++ b/tianshou/data/batch.py
@@ -1,6 +1,6 @@
 import torch
-import warnings
 import pprint
+import warnings
 import numpy as np
 from typing import Any, List, Union, Iterator, Optional
 
@@ -218,8 +218,16 @@ class Batch:
                 v.to_torch(dtype, device)
 
     def append(self, batch: 'Batch') -> None:
-        """Append a :class:`~tianshou.data.Batch` object to current batch."""
-        assert isinstance(batch, Batch), 'Only append Batch is allowed!'
+        warnings.warn('Method append will be removed soon, please use '
+                      ':meth:`~tianshou.data.Batch.cat`')
+        return self.cat(batch)
+
+    def cat(self, batch: 'Batch') -> None:
+        """Concatenate a :class:`~tianshou.data.Batch` object to current
+        batch.
+        """
+        assert isinstance(batch, Batch), \
+            'Only Batch is allowed to be concatenated!'
         for k, v in batch.__dict__.items():
             if k == '_meta':
                 self._meta.update(batch._meta)
@@ -235,9 +243,9 @@ class Batch:
             elif isinstance(v, list):
                 self.__dict__[k] += v
             elif isinstance(v, Batch):
-                self.__dict__[k].append(v)
+                self.__dict__[k].cat(v)
             else:
-                s = f'No support for append with type \
+                s = f'No support for method "cat" with type \
                       {type(v)} in class Batch.'
                 raise TypeError(s)
 
diff --git a/tianshou/data/buffer.py b/tianshou/data/buffer.py
index 592be5f..92756d5 100644
--- a/tianshou/data/buffer.py
+++ b/tianshou/data/buffer.py
@@ -413,7 +413,7 @@ class PrioritizedReplayBuffer(ReplayBuffer):
                 impt_weight=1 / np.power(
                     self._size * (batch.weight / self._weight_sum),
                     self._beta))
-            batch.append(impt_weight)
+            batch.cat(impt_weight)
         self._check_weight_sum()
         return batch, indice
 
diff --git a/tianshou/data/collector.py b/tianshou/data/collector.py
index ed75b4e..4ff0997 100644
--- a/tianshou/data/collector.py
+++ b/tianshou/data/collector.py
@@ -406,7 +406,7 @@ class Collector(object):
                 if batch_size and cur_batch or batch_size <= 0:
                     batch, indice = b.sample(cur_batch)
                     batch = self.process_fn(batch, b, indice)
-                    batch_data.append(batch)
+                    batch_data.cat(batch)
         else:
             batch_data, indice = self.buffer.sample(batch_size)
             batch_data = self.process_fn(batch_data, self.buffer, indice)