1. 兩個 iFrame:f1,f2

2. f1.htm:

function SCRL()
{
parent.window["f2"].document.body.scrollLeft = document.body.scrollLeft;
parent.window["f2"].document.body.scrollTop = document.body.scrollTop;
}

3. f2.htm:

function SCRL()
{
parent.window["f1"].document.body.scrollLeft = document.body.scrollLeft;
parent.window["f1"].document.body.scrollTop = document.body.scrollTop;
}

4. 兩邊的 Body 加上 onScroll="SCRL()"