谁能解释一下为什么不出界面呢

from PySide2 import QtWidgets
from PySide2.QtCore import *
from PySide2.QtWidgets import *
class Ui_Dialog(object):
def setupUi(self, Dialog):
if not Dialog.objectName():
Dialog.setObjectName(u"Dialog")
Dialog.resize(971, 717)
self.label = QLabel(Dialog)
self.label.setObjectName(u"label")
self.label.setGeometry(QRect(370, 260, 72, 15))
self.label_2 = QLabel(Dialog)
self.label_2.setObjectName(u"label_2")
self.label_2.setGeometry(QRect(370, 300, 72, 15))
self.label_3 = QLabel(Dialog)
self.label_3.setObjectName(u"label_3")
self.label_3.setGeometry(QRect(370, 350, 72, 15))
self.pushButton = QPushButton(Dialog)
self.pushButton.setObjectName(u"pushButton")
self.pushButton.setGeometry(QRect(410, 400, 93, 28))
self.pushButton.clicked.connect(self.ch)
self.lineEdit = QLineEdit(Dialog)
self.lineEdit.setObjectName(u"lineEdit")
self.lineEdit.setGeometry(QRect(470, 260, 113, 21))
self.lineEdit_2 = QLineEdit(Dialog)
self.lineEdit_2.setObjectName(u"lineEdit_2")
self.lineEdit_2.setGeometry(QRect(470, 300, 113, 21))
self.lineEdit_3 = QLineEdit(Dialog)
self.lineEdit_3.setObjectName(u"lineEdit_3")
self.lineEdit_3.setGeometry(QRect(470, 340, 113, 21))
self.retranslateUi(Dialog)
QMetaObject.connectSlotsByName(Dialog)
def ch(self):
rely=QMessageBox.information(self,"标题","消息正文",QMessageBox.yes | QMessageBox.No)
print(rely)
# setupUi
def retranslateUi(self, Dialog):
Dialog.setWindowTitle(QCoreApplication.translate("Dialog", u"Dialog", None))
self.label.setText(QCoreApplication.translate("Dialog", u"\u5185\u5f84;", None))
self.label_2.setText(QCoreApplication.translate("Dialog", u"\u5916\u5f84\uff1a", None))
self.label_3.setText(QCoreApplication.translate("Dialog", u"\u9ad8\uff1a", None))
self.pushButton.setText(QCoreApplication.translate("Dialog", u"\u63d0\u4ea4", None))
# retranslateUi

import sys

if name == "main":#相当于main入口
app = QtWidgets.QApplication(sys.argv) # 创建一个QApplication，即将开发的软件app
MainWindow = QtWidgets.QMainWindow() # QMainWindow装载需要的组件
ui = Ui_Dialog()#后面加上你所用类的文件（创建实例化对象）
ui.setupUi(MainWindow) # 执行类中的setupUi方法
d=Ui_Dialog
d.show()
MainWindow.show()
sys.exit(app.exec_()) # exit()或点击按钮退出app

去掉
d=Ui_Dialog
d.show()
这两句就可以了。
另外你的main入口函数写的不对，应该是 if __name__ == "__main__":
下面是可以运行的代码，如果有帮助望采纳。

from PySide2 import QtWidgets
from PySide2.QtCore import *
from PySide2.QtWidgets import *


class Ui_Dialog(object):

    def setupUi(self, Dialog):
        if not Dialog.objectName():
            Dialog.setObjectName(u"Dialog")
        Dialog.resize(971, 717)
        self.label = QLabel(Dialog)
        self.label.setObjectName(u"label")
        self.label.setGeometry(QRect(370, 260, 72, 15))
        self.label_2 = QLabel(Dialog)
        self.label_2.setObjectName(u"label_2")
        self.label_2.setGeometry(QRect(370, 300, 72, 15))
        self.label_3 = QLabel(Dialog)
        self.label_3.setObjectName(u"label_3")
        self.label_3.setGeometry(QRect(370, 350, 72, 15))
        self.pushButton = QPushButton(Dialog)
        self.pushButton.setObjectName(u"pushButton")
        self.pushButton.setGeometry(QRect(410, 400, 93, 28))
        self.pushButton.clicked.connect(self.ch)
        self.lineEdit = QLineEdit(Dialog)
        self.lineEdit.setObjectName(u"lineEdit")
        self.lineEdit.setGeometry(QRect(470, 260, 113, 21))
        self.lineEdit_2 = QLineEdit(Dialog)
        self.lineEdit_2.setObjectName(u"lineEdit_2")
        self.lineEdit_2.setGeometry(QRect(470, 300, 113, 21))
        self.lineEdit_3 = QLineEdit(Dialog)
        self.lineEdit_3.setObjectName(u"lineEdit_3")
        self.lineEdit_3.setGeometry(QRect(470, 340, 113, 21))
        self.retranslateUi(Dialog)
        QMetaObject.connectSlotsByName(Dialog)

    def ch(self):
        rely = QMessageBox.information(self, "标题", "消息正文", QMessageBox.yes | QMessageBox.No)
        print(rely)

    # setupUi
    def retranslateUi(self, Dialog):
        Dialog.setWindowTitle(QCoreApplication.translate("Dialog", u"Dialog", None))
        self.label.setText(QCoreApplication.translate("Dialog", u"\u5185\u5f84;", None))
        self.label_2.setText(QCoreApplication.translate("Dialog", u"\u5916\u5f84\uff1a", None))
        self.label_3.setText(QCoreApplication.translate("Dialog", u"\u9ad8\uff1a", None))
        self.pushButton.setText(QCoreApplication.translate("Dialog", u"\u63d0\u4ea4", None))
        # retranslateUi


import sys

if __name__ == "__main__":  # 相当于main入口
    app = QtWidgets.QApplication(sys.argv)  # 创建一个QApplication，即将开发的软件app
    MainWindow = QtWidgets.QMainWindow()  # QMainWindow装载需要的组件
    ui = Ui_Dialog()  # 后面加上你所用类的文件（创建实例化对象）
    ui.setupUi(MainWindow)  # 执行类中的setupUi方法
    MainWindow.show()
    sys.exit(app.exec_())  # exit()或点击按钮退出app

d=Ui_Dialog
d.show()
这里不对
ui = Ui_Dialog()这里已经实例化过了
直接
ui.show()
你的变量d没有关联MainWindow