diff --git a/paddlespeech/s2t/modules/embedding.py b/paddlespeech/s2t/modules/embedding.py
index 54324c2f6..f41a7b5d4 100644
--- a/paddlespeech/s2t/modules/embedding.py
+++ b/paddlespeech/s2t/modules/embedding.py
@@ -110,12 +110,10 @@ class PositionalEncoding(nn.Layer, PositionalEncodingInterface):
             paddle.Tensor: Encoded tensor. Its shape is (batch, time, ...)
             paddle.Tensor: for compatibility to RelPositionalEncoding, (batch=1, time, ...)
         """
-        T = x.shape[1]
         assert offset + x.shape[
             1] < self.max_len, "offset: {} + x.shape[1]: {} is larger than the max_len: {}".format(
                 offset, x.shape[1], self.max_len)
-        #TODO(Hui Zhang): using T = paddle.shape(x)[1], __getitem__ not support Tensor
-        pos_emb = self.pe[:, offset:offset + T]
+        pos_emb = self.pe[:, offset:offset + x.shape[1]]
         x = x * self.xscale + pos_emb
         return self.dropout(x), self.dropout(pos_emb)
 
@@ -164,6 +162,5 @@ class RelPositionalEncoding(PositionalEncoding):
             1] < self.max_len, "offset: {} + x.shape[1]: {} is larger than the max_len: {}".format(
                 offset, x.shape[1], self.max_len)
         x = x * self.xscale
-        #TODO(Hui Zhang): using paddle.shape(x)[1], __getitem__ not support Tensor
         pos_emb = self.pe[:, offset:offset + x.shape[1]]
         return self.dropout(x), self.dropout(pos_emb)
diff --git a/paddlespeech/s2t/modules/subsampling.py b/paddlespeech/s2t/modules/subsampling.py
index 88451ddd7..2775988a7 100644
--- a/paddlespeech/s2t/modules/subsampling.py
+++ b/paddlespeech/s2t/modules/subsampling.py
@@ -139,8 +139,8 @@ class Conv2dSubsampling4(Conv2dSubsampling):
         """
         x = x.unsqueeze(1)  # (b, c=1, t, f)
         x = self.conv(x)
-        b, c, t, f = paddle.shape(x)
-        x = self.out(x.transpose([0, 2, 1, 3]).reshape([b, t, c * f]))
+        b, c, t, f = x.shape
+        x = self.out(x.transpose([0, 2, 1, 3]).reshape([b, -1, c * f]))
         x, pos_emb = self.pos_enc(x, offset)
         return x, pos_emb, x_mask[:, :, :-2:2][:, :, :-2:2]