废话不多说,直接上代码:

<script>
    function showImg(e, id) {
        var image = document.getElementById(id);
        image.style.left = e.clientX + 20 + 'px';
        image.style.top = e.clientY + 30 + 'px';
        image.style.display = "block";
    }

    function hideImg(name) {
        document.getElementById(name).style.display = "none";
    }
</script>
    <img src="http://images.lolimay.cn/18-2-17/82883809.jpg" style="display:none;position:absolute" id="pic">
    <a onmousemove="showImg(event,'pic')" onmouseout="hideImg('pic')" style="cursor:pointer; ">鼠标移上显示图片</a>

演示: