90行写错了 。 需要两个 parentNode。removeChild删除的元素必须是 其子元素（不能嵌套）。
<style type="text/css">
.video{
width:100%;
height:500px;
}
#div1{
margin: auto;
border: 1px beige solid;
width: 512px;
text-align: left;
}
ul{
list-style-type: none;
list-style-image: url(../lxyzzy的副本/images/y.JPG);
}
.box{
width: 400px;
height: 150px;
border: 1px darkgray solid;
border-radius: 30px;
position: relative;
}
.box .touxiang{
width: 80px;
height: 80px;
background-size: 100% 100%;
background-image: url(../lxyzzy的副本/images/y.JPG);
position: absolute;
left: 10px;
top: 10px;
}
.box .nicheng{
width: 80px;
height:25px ;
position: absolute;
left: 10px;
top: 100px;
font-size: 12px;
text-align: center;
line-height: 25px;
}
.box .pinglun{
width: 290px;
height: 80px;
position: absolute;
top: 10px;
right: 10px;
}
.box .shijian{
width: 200px;
height: 25px;
position: absolute;
top: 100px;
left:100px;
}
</style>
<script>
window.onload=function(){
var oTxt = document.getElementById("txt");
var oBtn = document.getElementById("btn1");
var oUl1 = document.getElementById("ul1");
oBtn.onclick=function(){
var oBox = document.createElement("div");
oBox.className = "box";
//创建头像
var oDiv = document.createElement("div");
oDiv.className = "touxiang";
oBox.appendChild(oDiv);
var oDiv = document.createElement("div");
oDiv.className = "nicheng";
oDiv.innerHTML = "rich";
oBox.appendChild(oDiv);
var oDiv = document.createElement("div");
oDiv.className = "pinglun";
oDiv.innerHTML = oTxt.value;
oBox.appendChild(oDiv);
var oDiv = document.createElement("div");
oDiv.className = "shijian";
var oDate = new Date();
//oDate.getFullYear
oDiv.innerHTML ="评论时间 "+ oDate.getFullYear()+"年"+(oDate.getMonth()+1)+"月"+oDate.getDate()+"日"+" <a href='javascript:;'>删除</a>";
oBox.appendChild(oDiv);
oUl1.appendChild(oBox);
/*oBox.insertBefore(oUl1,oDiv[0]);*/
var aA = oDiv.getElementsByTagName("a");
for(var i = 0;i<aA.length;i++)
{
aA[i].onclick=function(){
console.log(this.parent)
//oUl1.removeChild(oBox); //这个 也可以
oUl1.removeChild(this.parentNode.parentNode); //这个也可以
}
}
}
}
</script>
<body>
<div>
<video width="320" height="240" controls class="video">
<source src="video/m.mp4" type="video/mp4">
您的浏览器不支持 video 标签。
</video>
</div>
<br>
<!-- 分界线 -->
<hr>
<h2 align="center"> 评论</h2>
<div id="div1" >
<textarea cols="70" rows="8" id="txt"></textarea><br/>
<input type="button" value="评论" id="btn1" />
<ul id="ul1"></ul>
</div>
</body>
