QMenu *MainMenu = new QMenu(this);
QAction *option = new QAction(MainMenu);
...
actionList<<option...
MainMenu->addActions(actionList);
QMenu *childMenu = new QMenu();
QAction *childact = new QAction(childMenu);
...
QList<QAction *> childActionList;
childActionList<<childact...
childMenu->addActions(childActionList);
option->setMenu(childMenu);//子菜单加入menu
MainMenu->addMenu(childMenu);//主菜单也要加menu
chileMenu->removeAction(childact);
没有removeActions