百度，谷歌之后都说用setHintSize(self,QCore.QSize(width,height)),然并卵，后来用qss修改就可以了，具体用法如下

# emaillist是我给QListWidget取得变量名，“#emaillist”后面加两个冒号表示选择器，即
“#emaillist::Item”表示选择所有的item

self.emaillist.setStyleSheet(_fromUtf8("#emaillist{background-color: rgb(242,242,242);}\n"
"#emaillist::Item{\n"
"width:260px;\n"
"height:50px;\n"
"}\n"
"#emaillist::Item:hover{\n"
"background-color: rgb(41, 189, 139);\n"
"}"))