<script>
function openNew(){
    window.open('b.html',null,"width=500px,height=300px");
}

</script>
<INPUT TYPE="button" value='  AA  ' onclick="openNew()">

------解决方案--------------------
a.html
HTML code

<script>
function openNew(){
   var newin =  window.open('b.html',null,"width=500px,height=300px");
}
setInterval('openNew()',5000);//5秒

</script>
<INPUT TYPE="button" value='  AA  ' onclick="openNew()">

------解决方案--------------------
楼上的这行代码得改改

var newin =  window.open('b.html',null,"width=500px,height=300px");


改成

var newin =  window.open('b.html','showinfo',"width=500px,height=300px");

保证打开的窗口不分开


------解决方案--------------------
窗口名称是一样的话，就是在同一个新窗口中打开

------解决方案--------------------
只有在A.html上下功夫