function setIframeHeight(iframe) {

              if (iframe) {

                  var iframeWin = iframe.contentWindow || iframe.contentDocument.parentWindow;

                  if (iframeWin.document.body) {

                      iframe.height = iframeWin.document.documentElement.scrollHeight || iframeWin.document.body.scrollHeight;

                  }

              }

            };

            window.onload = function () {

                setIframeHeight(document.getElementById('myiframe'));//iframe的id

}; 

<iframe onload="setIframeHeight(this)" id="myiframe" name="item-ifram" class="ZhaoShangJiaMeng-ifram" src="ZhaoShangJiaMeng-QuanYi.html" frameborder="0" scrolling="no" ></iframe>