*{
  padding: 0;
  margin: 0;
}
li{
  list-style-type: none;
}
.zoom{
  margin: 50px;
  position: relative;
}
.zoomMiddle{
  border: 1px solid #ccc;
  width: 300px;
  height: 300px;
  margin-bottom: 3px;
  position: relative;
}
.zoomMiddle img{
  width: 300px;
  height: 300px;
}
.mask{
  width: 100px;
  height: 100px;
  background: #abcdef;
  opacity:0.4;
  position: absolute;
  left: 0;
  top: 0;
  display: none;
}
.zoomSmall{
  -overflow: hidden;
  width: 302px;
  height: 54px;
}
.zoomSmall span{
  float: left;
  height: 52px;
  line-height: 52px;
  width: 10px;
  text-align: center;
  border: 1px solid #ccc;
  cursor: pointer;
}
.zoomSmall span.disable{
  cursor: default;
  background: #ccc;
}
.wrapSmallImg{
  float: left;
  height: 54px;
  width: 232px;
  /*background: #f00;*/
  position: relative;
  overflow: hidden;
}
.wrapSmallImg ul{
  width: 348px;
  /*background: #f00;*/
  position: absolute;
  left: 0;
  top: 0;
}
.wrapSmallImg ul li{
  float: left;
  width: 50px;
  height: 50px;
  border: 2px solid #ccc;
  margin: 0 2px;
  _display: inline;
  cursor: pointer;
}
.wrapSmallImg ul li.current{
  border: 2px solid orange;
}
.wrapSmallImg ul li img{
  width: 50px;
  height: 50px;
}
.zoomLarge{
  width: 350px;
  height: 350px;
  border: 1px solid #ccc;
  position: absolute;
  top: 0;
  left: 320px;
  overflow: hidden;
  display:none;
}
.zoomLarge img{
  width: 600px;
  height:600px;
  position: absolute;
  left: 0;
  top: 0;
}

zoom.html：

<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>放大鏡</title>
<link rel="stylesheet" href="zoom.css">
</head>
<body>
<input type="text" name="" id="">
<div class="zoom">
  <div class="zoomMiddle">
    <img src="1.jpg" alt="">
    <div class="mask"></div>
  </div>
  <div class="zoomSmall">
    <span class="left disable">&lt;</span>
    <div class="wrapSmallImg">
      <ul>
        <li class="current"><img src="1.jpg" alt=""></li>
        <li><img src="2.jpg" alt=""></li>
        <li><img src="3.jpg" alt=""></li>
        <li><img src="4.jpg" alt=""></li>
        <li><img src="5.jpg" alt=""></li>
        <li><img src="6.jpg" alt=""></li>
      </ul>
    </div>
    <span class="right">&gt;</span>
  </div>
  <div class="zoomLarge"><img src="1.jpg" alt=""></div>
</div>
<script src="jquery.js"></script>
<script src="zoom.js"></script>
</body>
</html>

zoom.js：

$(function(){
  var smallImgLi = $('.wrapSmallImg ul li');
  var smallImgLiLength = smallImgLi.size();
  var smallImgLiWidth = smallImgLi.outerWidth(true);
  var smallImgUl = $('.wrapSmallImg ul');
  var leftBtn = $('span.left');
  var rightBtn = $('span.right');
  var now = 0;
  var zoomMiddleDiv = $('.zoomMiddle');
  smallImgLi.mouseover(function(){
    $(this).addClass('current').siblings().removeClass('current');
    var thisSrc = $(this).children('img').attr('src');
    $('.zoomMiddle img').attr('src',thisSrc);
    $('.zoomLarge img').attr('src',thisSrc);
  });
  rightBtn.click(function(){
    //當(dāng)now=2的時候，我們不希望再讓他滾動了
    leftBtn.removeClass('disable');
    if(now>=smallImgLiLength-4){
      $(this).addClass('disable');
      now = smallImgLiLength-4;
    }else{
      now++;
      smallImgUl.animate({'left':-now*smallImgLiWidth},300);
    }
  });
  leftBtn.click(function(){
    if(now==0){
      now=0;
    }else{
      now--;
      smallImgUl.animate({'left':'+='+smallImgLiWidth},300);
    }
  });
  zoomMiddleDiv.mousemove(function(e){
    $('.mask').show();
    $('.zoomLarge').show();
    zoomMiddleDivOffset = zoomMiddleDiv.offset();
    var x = e.pageX - zoomMiddleDivOffset.left - $('.mask').width()/2;
    var y = e.pageY - zoomMiddleDivOffset.top - $('.mask').height()/2;
    if(x<=0){
      x=0;
    }else if(x>=zoomMiddleDiv.width()-$('.mask').width()){
      x = zoomMiddleDiv.width()-$('.mask').width();
    }
    if(y<=0){
      y=0;
    }else if(y>=zoomMiddleDiv.height()-$('.mask').height()){
      y = zoomMiddleDiv.height()-$('.mask').height();
    }
    var percentageX = x/(zoomMiddleDiv.width()-$('.mask').width());
    var percentageY = y/(zoomMiddleDiv.height()-$('.mask').height());
    $('.zoomLarge img').css({
      left:-percentageX*(600-$('.zoomLarge').width()),
      top:-percentageY*(600-$('.zoomLarge').height())
    });
    $('input').val(percentageX+','+percentageY)
    $('.mask').css({
      'left':x+'px',
      'top':y+'px'
    });
  });
  zoomMiddleDiv.mouseout(function(){
    $('.mask').hide();
    $('.zoomLarge').hide();
  });
});

效果圖如下：