改为这样:<form name="form1" method="post" action="" onsubmit="return CheckForm(this)" target="TestIframe">
<input name="UserName" type="text" size="30" maxlength="30">
<input name="Pass" type="password" size="30" maxlength="30">
<input type="submit" name="Submit" value="登 录" onClick="return CheckForm(this.theForm)";"class="BUTT">
</form>
<input name="UserName" type="text" size="30" maxlength="30">
<input name="Pass" type="password" size="30" maxlength="30">
<input type="submit" name="Submit" value="登 录" onClick="return CheckForm(this.theForm)";"class="BUTT">
</form>
应该说form1.submit()吧
============================================
<SCRIPT LANGUAGE="JavaScript">
window.name='TestIframe';
function CheckForm(theForm){
if (document.all.UserName.value==''){alert("请输入用户名!");document.all.UserName.focus();return false;}
if (document.all.Pass.value==''){alert("请输入密码!");document.all.Pass.focus();return false;}
document.all.form1.submit();
return true;
}
</SCRIPT>
<form name="form1" method="post" action=""target="TestIframe">
<input name="UserName" type="text" size="30" maxlength="30">
<input name="Pass" type="password" size="30" maxlength="30">
<input type="button" name="Submit" value="登 录" onClick="return CheckForm(this);"class="BUTT">
</form>