--- a
+++ b/tools/model_converters/swin2mmseg.py
@@ -0,0 +1,87 @@
+# Copyright (c) OpenMMLab. All rights reserved.
+import argparse
+import os.path as osp
+from collections import OrderedDict
+
+import mmcv
+import torch
+from mmcv.runner import CheckpointLoader
+
+
+def convert_swin(ckpt):
+    new_ckpt = OrderedDict()
+
+    def correct_unfold_reduction_order(x):
+        out_channel, in_channel = x.shape
+        x = x.reshape(out_channel, 4, in_channel // 4)
+        x = x[:, [0, 2, 1, 3], :].transpose(1,
+                                            2).reshape(out_channel, in_channel)
+        return x
+
+    def correct_unfold_norm_order(x):
+        in_channel = x.shape[0]
+        x = x.reshape(4, in_channel // 4)
+        x = x[[0, 2, 1, 3], :].transpose(0, 1).reshape(in_channel)
+        return x
+
+    for k, v in ckpt.items():
+        if k.startswith('head'):
+            continue
+        elif k.startswith('layers'):
+            new_v = v
+            if 'attn.' in k:
+                new_k = k.replace('attn.', 'attn.w_msa.')
+            elif 'mlp.' in k:
+                if 'mlp.fc1.' in k:
+                    new_k = k.replace('mlp.fc1.', 'ffn.layers.0.0.')
+                elif 'mlp.fc2.' in k:
+                    new_k = k.replace('mlp.fc2.', 'ffn.layers.1.')
+                else:
+                    new_k = k.replace('mlp.', 'ffn.')
+            elif 'downsample' in k:
+                new_k = k
+                if 'reduction.' in k:
+                    new_v = correct_unfold_reduction_order(v)
+                elif 'norm.' in k:
+                    new_v = correct_unfold_norm_order(v)
+            else:
+                new_k = k
+            new_k = new_k.replace('layers', 'stages', 1)
+        elif k.startswith('patch_embed'):
+            new_v = v
+            if 'proj' in k:
+                new_k = k.replace('proj', 'projection')
+            else:
+                new_k = k
+        else:
+            new_v = v
+            new_k = k
+
+        new_ckpt[new_k] = new_v
+
+    return new_ckpt
+
+
+def main():
+    parser = argparse.ArgumentParser(
+        description='Convert keys in official pretrained swin models to'
+        'MMSegmentation style.')
+    parser.add_argument('src', help='src model path or url')
+    # The dst path must be a full path of the new checkpoint.
+    parser.add_argument('dst', help='save path')
+    args = parser.parse_args()
+
+    checkpoint = CheckpointLoader.load_checkpoint(args.src, map_location='cpu')
+    if 'state_dict' in checkpoint:
+        state_dict = checkpoint['state_dict']
+    elif 'model' in checkpoint:
+        state_dict = checkpoint['model']
+    else:
+        state_dict = checkpoint
+    weight = convert_swin(state_dict)
+    mmcv.mkdir_or_exist(osp.dirname(args.dst))
+    torch.save(weight, args.dst)
+
+
+if __name__ == '__main__':
+    main()