import sys
from PyQt5.QtWidgets import QApplication, QWidget
if __name__ == '__main__':
    app = QApplication(sys.argv)
    w = QWidget()
    w.resize(250, 150)
    w.move(300, 300)
    w.setWindowTitle('Simple')
    w.show()    
    sys.exit(app.exec_())

#!/usr/bin/python3
# -*- coding: utf-8 -*-
import sys
from PyQt5.QtWidgets import QApplication, QWidget
from PyQt5.QtGui import QIcon
class Example(QWidget):    
    def __init__(self):
        super().__init__()        
        self.initUI()       
    def initUI(self):        
        self.setGeometry(300, 300, 300, 220)
        self.setWindowTitle('Icon')
        self.setWindowIcon(QIcon('web.png'))    
        self.show()        
if __name__ == '__main__':    
    app = QApplication(sys.argv)
    ex = Example()
    sys.exit(app.exec_())

1. 响应事件EVENT：

#!/usr/bin/python3
# -*- coding: utf-8 -*-

import sys
from PyQt5.QtWidgets import QWidget, QPushButton, QApplication
from PyQt5.QtCore import QCoreApplication

def closeapp():
    sys.exit(app.exec_())
class Example(QWidget):
    
    def __init__(self):
        super().__init__()
        
        self.initUI()
        
        
    def initUI(self):               
        
        qbtn = QPushButton('Quit', self)
        #qbtn.clicked.connect(QCoreApplication.instance().quit)
        qbtn.clicked.connect(closeapp)
        qbtn.resize(qbtn.sizeHint())
        qbtn.move(50, 50)       
        
        self.setGeometry(300, 300, 250, 150)
        self.setWindowTitle('Quit button')    
        self.show()
        
        
if __name__ == '__main__':
    
    app = QApplication(sys.argv)
    ex = Example()
    sys.exit(app.exec_())

2. Sender——信号从哪儿来：

#!/usr/bin/python3
# -*- coding: utf-8 -*-
import sys
from PyQt5.QtWidgets import QMainWindow, QPushButton, QApplication
class Example(QMainWindow):
    
    def __init__(self):
        super().__init__()
        
        self.initUI()
        
        
    def initUI(self):      

        btn1 = QPushButton("Button 1", self)
        btn1.move(30, 50)

        btn2 = QPushButton("Button 2", self)
        btn2.move(150, 50)
      
        btn1.clicked.connect(self.buttonClicked)            
        btn2.clicked.connect(self.buttonClicked)
        
        self.statusBar()
        
        self.setGeometry(300, 300, 290, 150)
        self.setWindowTitle('Event sender')
        self.show()
        
        
    def buttonClicked(self):
      
        sender = self.sender()
        self.statusBar().showMessage(sender.text() + ' was pressed')
        
        
if __name__ == '__main__':
    
    app = QApplication(sys.argv)
    ex = Example()
sys.exit(app.exec_())

3. 模态对话框，首先要是一个对话框！！！

#!/usr/bin/python3
# -*- coding: utf-8 -*-
import sys
from PyQt5.QtWidgets import QDialog,QMainWindow, QPushButton, QApplication
class Example(QMainWindow):
    
    def __init__(self):
        super().__init__()
        
        self.initUI()
        
        
    def initUI(self):      

        btn1 = QPushButton("Button 1", self)
        btn1.move(30, 50)

        btn2 = QPushButton("Button 2", self)
        btn2.move(150, 50)
      
        btn1.clicked.connect(self.buttonClicked)            
        btn2.clicked.connect(self.buttonClicked)
        
        self.statusBar()
        
        self.setGeometry(300, 300, 290, 150)
        self.setWindowTitle('Event sender')
        self.show()
        
        
    def buttonClicked(self):
      
        sender = self.sender()
        self.statusBar().showMessage(sender.text() + ' was pressed')
        d = Dialog2()
        d.setModal(True)
        d.exec_()
        print('close')
        
class Dialog2(QDialog):
    
    def __init__(self):
        super().__init__()
        
        self.initUI()
        
        
    def initUI(self):               
        
        qbtn = QPushButton('Quit', self)
        qbtn.resize(qbtn.sizeHint())
        qbtn.move(50, 50)       
        
        self.setGeometry(300, 300, 250, 150)
        self.setWindowTitle('Quit button')    
       
if __name__ == '__main__':
    
    app = QApplication(sys.argv)
    ex = Example()
    sys.exit(app.exec_())

4 运用QT Desinger

仅适用代码构建GUI，有一些不方便，可以借用QT Designer将GUI设计出来，保存为xxx.ui文件，然后通过pyqt5自带的pyuic5命令将ui文件转换问可用的py文件，下面在Designer中简单设计一个界面，包含Menu，status Bar和一个按钮，保存为testGUI.ui。

然后再cmd命令行中输入：G:\work\python>pyuic5 testGUI.ui -o testGUI.py便将ui文件转换为pyqt中可以使用的py文件，代码内容如下：从生成的代码分析。

class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(800, 600)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.pushButton = QtWidgets.QPushButton(self.centralwidget)
        self.pushButton.setGeometry(QtCore.QRect(20, 40, 36, 36))
        self.pushButton.setObjectName("pushButton")
        MainWindow.setCentralWidget(self.centralwidget)
        self.menubar = QtWidgets.QMenuBar(MainWindow)
        self.menubar.setGeometry(QtCore.QRect(0, 0, 800, 23))
        self.menubar.setObjectName("menubar")
        self.menu = QtWidgets.QMenu(self.menubar)
        self.menu.setObjectName("menu")
        MainWindow.setMenuBar(self.menubar)
        self.statusbar = QtWidgets.QStatusBar(MainWindow)
        self.statusbar.setObjectName("statusbar")
        MainWindow.setStatusBar(self.statusbar)
        self.actionNew = QtWidgets.QAction(MainWindow)
        self.actionNew.setObjectName("actionNew")
        self.actionSave = QtWidgets.QAction(MainWindow)
        self.actionSave.setObjectName("actionSave")
        self.actionLoad = QtWidgets.QAction(MainWindow)
        self.actionLoad.setObjectName("actionLoad")
        self.menu.addAction(self.actionNew)
        self.menu.addAction(self.actionSave)
        self.menu.addAction(self.actionLoad)
        self.menubar.addAction(self.menu.menuAction())

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

    def retranslateUi(self, MainWindow):
        _translate = QtCore.QCoreApplication.translate
        MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))
        self.pushButton.setText(_translate("MainWindow", "00"))
        self.menu.setTitle(_translate("MainWindow", "游戏"))
        self.actionNew.setText(_translate("MainWindow", "新建游戏"))
        self.actionSave.setText(_translate("MainWindow", "保存"))
        self.actionLoad.setText(_translate("MainWindow", "读取"))

若要使用Ui_MainWindow先创建一个QMainWindow，然后传递给ui初始化。

app = QApplication(sys.argv)

    window = QMainWindow()
    ui = Ui_MainWindow()
    ui.setupUi(window)
    window.show()
    sys.exit(app.exec_())