#wai{

    width:300px;

    height: 300px;

    border: 1px solid red;

}   

img{

    width: 100%;

    height: 100%;

    display: none;

}

<div id="wai" onmouseover="qing()" onmouseout="hui()">

    <img src="timg.jpg"/style="display: block;">

    <img src="timg1.jpg"/>

    <img src="timg2.jpg"/>

    <img src="timg3.jpg"/>

</div>

<!--四个点的div-->
<div id="dianbox">
	<div class="dian" style="border-color: green;" onclick="yuan(this,'0')" onmouseover="qing()" onmouseout="hui()">
	</div>
	<div class="dian" onclick="yuan(this,'1')" onmouseover="qing()" onmouseout="hui()">
	</div>
	<div class="dian" onclick="yuan(this,'2')" onmouseover="qing()" onmouseout="hui()">
	</div>
	<div class="dian" onclick="yuan(this,'3')" onmouseover="qing()" onmouseout="hui()">
	</div>	
</div>

<!--左箭头div-->
<div id="lbox" onclick="zuoyou(-1)" onmouseover="qing()" onmouseout="hui()">
	<br>
	<div id="l">
	</div>
</div>

<!--右箭头div-->
<div id="lbox" onclick="zuoyou(-1)" onmouseover="qing()" onmouseout="hui()">
	<br>
	<div id="l">
	</div>
</div>

定义计时器

var timer = setInterval("lun()",2000);

清除计时器函数

function qing(){

    window.clearInterval(timer);

}

恢复计时器函数

function hui(){

    timer = setInterval("lun()",2000);

}

function lun(){ 

//  图片轮播

    bs++;

    var img = document.getElementsByTagName("img");

    if(bs>= img.length){

        bs=0;

    }

    for (i = 0;i<img.length;i++) {

        img[i].style.display="none";

    }

    img[bs].style.display="block";

//  圆点变色

    var dian = document.getElementsByClassName("dian");

    for (j = 0;j < img.length;j++) {

        dian[j].style.borderColor="red";

    }

    dian[bs].style.borderColor="green";

}

//点圆换图清除定时器

    function yuan(x,y){

        bs=y;

        var img = document.getElementsByTagName("img");

        for(i = 0;i<img.length;i++){

            img[i].style.display="none";

        }

        img[y].style.display="block";

        var dian = document.getElementsByClassName("dian");

        for (j = 0;j<dian.length;j++) {

            dian[j].style.borderColor="red";

        }

        x.style.borderColor="green";

    }

function zuoyou(z){

    bs=bs+z;

    if(bs==4){

        bs=0;

    }

    if(bs<0){

        bs=3;

    }

    var img = document.getElementsByTagName("img");

    for(i = 0;i<img.length;i++){

        img[i].style.display="none";

    }

    img[bs].style.display="block";

    var dian = document.getElementsByClassName("dian");

    for (j=0;j<dian.length;j++) {

        dian[j].style.borderColor="red";

    }

    dian[bs].style.borderColor="green";

}