html:
<a href="javascript:;" class="a-upload">
<input type="file" name="" id="">点击这里上传文件
</a>
css:
.a-upload {
padding: 4px 10px;
height: 20px;
line-height: 20px;
position: relative;
cursor: pointer;
color: #888;
background: #fafafa;
border: 1px solid #ddd;
border-radius: 4px;
overflow: hidden;
display: inline-block;
*display: inline;
text-decoration: none;
*zoom: 1
}
.a-upload input {
position: absolute;
font-size: 100px;
right: 0;
top: 0;
opacity: 0;
filter: alpha(opacity=0);
cursor: pointer;
color: #444;
background: #eee;
border-color: #ccc;
text-decoration: none
}
.a-upload:hover {
color: #ffffff;
background: #ff6f29;
border-color: #ff6f29;
text-decoration: none
}
效果：
总结：
input[type="file"]外面套盒子 设置overflow：hidden，input本身设置大小让其占满父盒子，设置opacity：0；
最后样式调整父盒子样式
