A: 

Use valign attribute of td tag.

..
<td valign="top">

</td>

EDIT:

Try this,

<table>
  <tr>
    <td><input type="text" /></td>
      <td><iframe scrolling="no" height="21px" 
          frameborder="0" width="62px" marginheight="0" marginwidth="0" 
          src="http://maishudi.com/Server/SecCode.php"&gt;
    </iframe>
    </td>
  </tr>
</table>
adatapost
I've already used valign attribute of td tag,but not working
Shore
You could easily tell us without downvoting.
adatapost
A: 

Use two td's, one for the input, and one for the iframe:

Or don't use tables at all, position the items using CSS, with the float property:

CMS
Why valign failed to work in a single td?
Shore