qss相关语法，请百度

//新建qss文件.例如myStyl.qss 
QPushButton#IM_btn_hall {
	background-image: url(Resources/IM/im_btn_hall_normal.png);
	border:none;
}
QPushButton#IM_btn_hall:hover {
	background-image: url(Resources/IM/im_btn_hall_hover.png);
	border:none;
}
QWidget#im_wid_titile {
	border-image: url(Resources/IM/im_title_top.png);
}

	//加载qss样式
	QFile styleSheet("qss/myStyle.qss");
	if (!styleSheet.open(QIODevice::ReadOnly))
	{
		qWarning("Can't open the style sheet file.");
		return;
	}
	qApp->setStyleSheet(styleSheet.readAll());