实现代码

model 为私有变量，QStandardItemModel *model;

void ParamSettingDlg::GetNode()
{
    for(int i = 0;i < model->rowCount() ;i++)
    {
        QStandardItem *item = model->item(i);

        qDebug() <<"item = " << item->text();
        GetItem(model->item(i) );
    }
}

GetItem 为递归函数，这样可以遍历到所有的节点

void ParamSettingDlg::GetItem(QStandardItem *item)
{
    Q_ASSERT(item);
    if(item->hasChildren())
    {
        for(int i = 0;i < item->rowCount() ;i++)
        {
            QStandardItem * childitem = item->child(i);
            qDebug() << "childitem = " << childitem->text();
            GetItem(childitem);
        }
    }
}

遍历所有节点查找并选中这一节点

for(int i = 0;i < standardModel_down->rowCount() ;i++)
{
     QStandardItem *item = standardModel_down->item(i);
     Q_ASSERT(item);
     if(item->hasChildren())
     {
         for(int i = 0;i < item->rowCount() ;i++)
         {
             QStandardItem * childitem = item->child(i);
             qDebug() << "childitem = " << childitem->text();
             if(childitem->text() == fileName1)
             {
                 ui->treeView_down->setCurrentIndex(childitem->index());
             }
         }
     }
     qDebug() <<"item = " << item->text();
 }