diff --git a/fastNLP/core/preprocess.py b/fastNLP/core/preprocess.py
index 77df6b51..0cfe526e 100644
--- a/fastNLP/core/preprocess.py
+++ b/fastNLP/core/preprocess.py
@@ -269,7 +269,7 @@ class ClassPreprocess(BasePreprocess):
 
             for word in sent:
                 if word not in word2index:
-                    word2index[word[0]] = len(word2index)
+                    word2index[word] = len(word2index)
         return word2index, label2index
 
     def to_index(self, data):
diff --git a/fastNLP/models/cnn_text_classification.py b/fastNLP/models/cnn_text_classification.py
index b6dcafb3..fc7388a5 100644
--- a/fastNLP/models/cnn_text_classification.py
+++ b/fastNLP/models/cnn_text_classification.py
@@ -5,7 +5,7 @@ import torch
 import torch.nn as nn
 
 # import torch.nn.functional as F
-from fastNLP.modules.encoder.conv_maxpool import ConvMaxpool
+import fastNLP.modules.encoder as encoder
 
 
 class CNNText(torch.nn.Module):
@@ -18,22 +18,22 @@ class CNNText(torch.nn.Module):
     def __init__(self, args):
         super(CNNText, self).__init__()
 
-        class_num = args["num_classes"]
+        num_classes = args["num_classes"]
         kernel_nums = [100, 100, 100]
         kernel_sizes = [3, 4, 5]
-        embed_num = args["vocab_size"]
+        vocab_size = args["vocab_size"]
         embed_dim = 300
         pretrained_embed = None
         drop_prob = 0.5
 
         # no support for pre-trained embedding currently
-        self.embed = nn.Embedding(embed_num, embed_dim, padding_idx=0)
-        self.conv_pool = ConvMaxpool(
+        self.embed = encoder.embedding.Embedding(vocab_size, embed_dim)
+        self.conv_pool = encoder.conv_maxpool.ConvMaxpool(
             in_channels=embed_dim,
             out_channels=kernel_nums,
             kernel_sizes=kernel_sizes)
         self.dropout = nn.Dropout(drop_prob)
-        self.fc = nn.Linear(sum(kernel_nums), class_num)
+        self.fc = encoder.linear.Linear(sum(kernel_nums), num_classes)
 
     def forward(self, x):
         x = self.embed(x)  # [N,L] -> [N,L,C]
diff --git a/fastNLP/modules/encoder/__init__.py b/fastNLP/modules/encoder/__init__.py
index b4e689a7..71b786b9 100644
--- a/fastNLP/modules/encoder/__init__.py
+++ b/fastNLP/modules/encoder/__init__.py
@@ -2,8 +2,10 @@ from .embedding import Embedding
 from .linear import Linear
 from .lstm import Lstm
 from .conv import Conv
+from .conv_maxpool import ConvMaxpool
 
 __all__ = ["Lstm",
            "Embedding",
            "Linear",
-           "Conv"]
+           "Conv",
+           "ConvMaxpool"]
diff --git a/fastNLP/modules/encoder/conv_maxpool.py b/fastNLP/modules/encoder/conv_maxpool.py
index 0012dce7..f666e7f9 100644
--- a/fastNLP/modules/encoder/conv_maxpool.py
+++ b/fastNLP/modules/encoder/conv_maxpool.py
@@ -4,6 +4,7 @@
 import torch
 import torch.nn as nn
 import torch.nn.functional as F
+from torch.nn.init import xavier_uniform_
 
 
 class ConvMaxpool(nn.Module):
@@ -21,6 +22,7 @@ class ConvMaxpool(nn.Module):
             if isinstance(kernel_sizes, int):
                 out_channels = [out_channels]
                 kernel_sizes = [kernel_sizes]
+
             self.convs = nn.ModuleList([nn.Conv1d(
                 in_channels=in_channels,
                 out_channels=oc,
@@ -31,6 +33,9 @@ class ConvMaxpool(nn.Module):
                 groups=groups,
                 bias=bias)
                 for oc, ks in zip(out_channels, kernel_sizes)])
+
+            for conv in self.convs:
+                xavier_uniform_(conv.weight)  # weight initialization
         else:
             raise Exception(
                 'Incorrect kernel sizes: should be list, tuple or int')