我试了一下还是不行,到底什么原因呢?
guoyou::guoyou(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::guoyou)
{
    ui->setupUi(this);
    ui->dateTimeEdit->setDate(QDate::currentDate());
    ui->dateTimeEdit->setTime(QTime::currentTime());
    QTimer *timer=new QTimer(this);
    timer->start(1000);
    connect(timer,SIGNAL(timeout()),ui->dateTimeEdit,SLOT(setTime()));
}
void guoyou::setTime()
{
    ui->dateTimeEdit->setDate(QDate::currentDate());
    ui->dateTimeEdit->setTime(QTime::currentTime());
}