这种样式的美化， 能气死个人，css 一个单词搞定，非要 在qss中。多少个单词不知道了。 

	m_tree_widget->setStyleSheet(
		"QTreeView{background:transparent; selection-background-color:transparent;}"
		"QTreeView::branch{border-left:1px solid #0D85FF;border-top:1px solid #0D85FF;border-bottom:1px solid #0D85FF;}"
		"QTreeView::branch:has-siblings:!adjoins-item {border-left:none;border-top:1px solid #0D85FF;border-bottom:1px solid #0D85FF;}"
		"QTreeView::branch:has-siblings:adjoins-item {border-left:none;border-top:1px solid #0D85FF;border-bottom:1px solid #0D85FF;}"
		"QTreeView::branch:!has-children:!has-siblings:adjoins-item {border-left:none;border-top:1px solid #0D85FF;border-bottom:1px solid #0D85FF;}"
		"QTreeView::branch:closed:has-children:has-siblings{border-left:none;border-top:1px solid #0D85FF;border-bottom:1px solid #0D85FF;}"
		"QTreeView::branch:has-children:!has-siblings:closed{border-left:none;border-top:1px solid #0D85FF;border-bottom:1px solid #0D85FF;}"
		"QTreeView::branch:open:has-children:has-siblings {border-left:none;border-top:1px solid #0D85FF;border-bottom:1px solid #0D85FF;}"
		"QTreeView::branch:open:has-children:!has-siblings {border-left:none;border-top:1px solid #0D85FF;border-bottom:1px solid #0D85FF; }"
		
		"QTreeView::item::first{border-right:1px solid #0D85FF;color:#01A7FD;}"
		"QTreeView::item::last{border-right:1px solid #0D85FF; color:#FFFFF;}"
		"QTreeView::item{height:40px;border-top:1px solid #0D85FF; border-bottom:1px solid #0D85FF;}"
		
		"QTreeView::item:selected{border-top:1px solid #0D85FF; border-bottom:1px solid #0D85FF;}"
		"QTreeView::item::last:selected{border-right:1px solid #0D85FF;}"
		"QTreeView::branch:selected{border-left:1px solid #0D85FF;border-top:1px solid #0D85FF;border-bottom:1px solid #0D85FF;}"
	);	

 最终效果

参考 

QTreeWidget样式qss_qtreewidget qss-CSDN博客