根据 HTML5编辑器草案规范，具有href元素的图像和锚点都是默认拖动的元素。您的主机可能是捕获dragstart事件，从而阻止了div的发生。尝试在您的< img> 和< a> 元素上设置draggable =false。

As per the HTML5 Editor's Draft spec, Images and Anchors with a href element are both elements that are, by default draggable. Your anchor is probably capturing the dragstart event, preventing the div from ever getting it. Try setting draggable="false" on your <img> and <a> elements.

<div draggable="true" id="item" style="margin:20px;background:red;height:400px;width:400px;">
<a href="#" target="_blank" draggable="false">
    <img style="margin:40px;" src="http://www.placekitten.com/100/100" alt="" draggable="false">
</a>

你的小提琴甚至不在Ubuntu下，Chrome在Chrome上拖动img元素，所以除此之外您可能还有其他问题。

Your fiddle doesn't even work dragging the img element for me in Chrome under Ubuntu, so you may have other issues besides this.