试试这个吧。

<table style="width: 100%">
    <tr>
        <th style="width: 20%">
           column 1
        </th>
        <th style="width: 40%">
           column 2
        </th>
        <th style="width: 40%">
           column 3
        </th>
    </tr>
    <tr>
        <td style="width: 20%">
           value 1
        </td>
        <td style="width: 40%">
           value 2
        </td>
        <td style="width: 40%">
           value 3
        </td>
    </tr>
</table>

<table>
  <col width="130">
  <col width="80">
  <tr>
    <th>Month</th>
    <th>Savings</th>
  </tr>
  <tr>
    <td>January</td>
    <td>$100</td>
  </tr>
  <tr>
    <td>February</td>
    <td>$80</td>
  </tr>
</table>

Demo

Table {Table -layout: fixed;｝ .subject{宽度:70%;｝ <表> < tr > 从< / th < th > > < th class = "主题" > < / th >主题 < th > < / th >日期 < / tr > 表> < /

不要使用border属性，使用CSS来满足所有的样式需求。

<table style="border:1px; width:100%;">
    <tr>
            <th style="width:15%;">From</th>
            <th style="width:70%;">Subject</th>
            <th style="width:15%;">Date</th>
    </tr>
... rest of the table code...
</table>

但是像这样嵌入CSS是很糟糕的做法——应该使用CSS类，并将CSS规则放在外部CSS文件中。

这里有另一种在CSS中实现它的最小方法，即使在不支持的旧浏览器中也能工作:n -child和类似的选择器:http://jsfiddle.net/3wZWt/。

HTML:

<table>
    <tr>
        <th>From</th>
        <th>Subject</th>
        <th>Date</th>
    </tr>
    <tr>
        <td>Dmitriy</td>
        <td>Learning CSS</td>
        <td>7/5/2014</td>
    </tr>
</table>

CSS:

table {
    border-collapse: collapse;
    width: 100%;
}

tr > * {
    border: 1px solid #000;
}

tr > th + th {
    width: 70%;
}

tr > th + th + th {
    width: 15%;
}

这是我的两点建议。

Using classes. There is no need to specify width of the two other columns as they will be set to 15% each automatically by the browser. table { table-layout: fixed; } .subject { width: 70%; } <table> <tr> <th>From</th> <th class="subject">Subject</th> <th>Date</th> </tr> </table> Without using classes. Three different methods but the result is identical. a) table { table-layout: fixed; } th+th { width: 70%; } th+th+th { width: 15%; } <table> <tr> <th>From</th> <th>Subject</th> <th>Date</th> </tr> </table> b) table { table-layout: fixed; } th:nth-of-type(2) { width: 70%; } <table> <tr> <th>From</th> <th>Subject</th> <th>Date</th> </tr> </table> c) This one is my favourite. Same as b) but with better browser support. table { table-layout: fixed; } th:first-child+th { width: 70%; } <table> <tr> <th>From</th> <th>Subject</th> <th>Date</th> </tr> </table>