主窗体

    # 为基础设置菜单中的QAction绑定triggered信号
    self.menu.triggered[QtWidgets.QAction].connect(self.openSet)

    self.menu.triggered[QtWidgets.QAction].connect(self.openSett)

    self.retranslateUi(MainWindow)
    QtCore.QMetaObject.connectSlotsByName(MainWindow)

    datatime=QtCore.QDateTime.currentDateTime()   # 获取当前日期时间
    time=datatime.toString("yyyy-MM-dd HH:mm:ss")

    self.statusbar.showMessage("当前登录用户："  + " | 登录时间：" + time + "  | 版权",0)



#基础设置对应的槽函数
def openSet(self,m):
    import tianjia,yuandata
    # self.second=tianjia.Ui_MainWindow()
    if m.text()=='添加数据':
        self.m=tianjia.Ui_MainWindow()
        self.m.show()
    elif m.text()=='修改数据':
        self.m=yuandata.Ui_MainWindow()
        self.m.show()
def openSett(self,s):
    import yuandata
    if s.text()=='加载数据':
        self.s=yuandata.Ui_MainWindow()
        self.s.show()

子窗体yuandata.py

from PyQt5 import QtCore, QtGui, QtWidgets
from PyQt5.QtWidgets import *
import sys
sys.path.append("../") # 返回上层路径
class Ui_MainWindow(QMainWindow):
    # 构造方法
    def __init__(self):
        super(Ui_MainWindow, self).__init__()
        self.setWindowFlags(QtCore.Qt.MSWindowsFixedSizeDialogHint)  # 只显示最小化和关闭按钮
        self.setupUi(self)  # 初始化窗体设置

    def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(751, 431)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.lineEdit = QtWidgets.QLineEdit(self.centralwidget)
        self.lineEdit.setGeometry(QtCore.QRect(30, 50, 61, 21))
        self.lineEdit.setObjectName("lineEdit")
        self.label = QtWidgets.QLabel(self.centralwidget)
        self.label.setGeometry(QtCore.QRect(20, 10, 121, 41))
        self.label.setObjectName("label")
        self.columnView = QtWidgets.QColumnView(self.centralwidget)
        self.columnView.setGeometry(QtCore.QRect(0, 0, 751, 431))
        self.columnView.setObjectName("columnView")
        self.pushButton = QtWidgets.QPushButton(self.centralwidget)
        self.pushButton.setGeometry(QtCore.QRect(590, 30, 61, 41))
        self.pushButton.setObjectName("pushButton")
        self.label_3 = QtWidgets.QLabel(self.centralwidget)
        self.label_3.setGeometry(QtCore.QRect(120, 10, 121, 41))
        self.label_3.setAlignment(QtCore.Qt.AlignCenter)
        self.label_3.setObjectName("label_3")
        self.lineEdit_2 = QtWidgets.QLineEdit(self.centralwidget)
        self.lineEdit_2.setGeometry(QtCore.QRect(150, 50, 61, 21))
        self.lineEdit_2.setObjectName("lineEdit_2")
        self.label_2 = QtWidgets.QLabel(self.centralwidget)
        self.label_2.setGeometry(QtCore.QRect(250, 10, 121, 41))
        self.label_2.setObjectName("label_2")
        self.lineEdit_3 = QtWidgets.QLineEdit(self.centralwidget)
        self.lineEdit_3.setGeometry(QtCore.QRect(270, 50, 61, 21))
        self.lineEdit_3.setObjectName("lineEdit_3")
        self.label_4 = QtWidgets.QLabel(self.centralwidget)
        self.label_4.setGeometry(QtCore.QRect(390, 10, 121, 41))
        self.label_4.setObjectName("label_4")

def retranslateUi(self, MainWindow):
    _translate = QtCore.QCoreApplication.translate
    MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))
    self.label.setText(_translate("MainWindow", "ul（长度的误差）"))
    self.pushButton.setText(_translate("MainWindow", "输出数据"))
    self.label_3.setText(_translate("MainWindow", "l(长度)"))
    self.label_2.setText(_translate("MainWindow", "i（选取数据的组数）"))
    self.label_4.setText(_translate("MainWindow", "t（样本的天数）"))
    self.label_5.setText(_translate("MainWindow", "Time"))
    self.label_6.setText(_translate("MainWindow", "C/C0"))
    self.label_7.setText(_translate("MainWindow", "RSD%"))