关键代码：

# 设置窗口图标    icon = QtGui.QIcon()    icon.addPixmap(QtGui.QPixmap("logo.ico"), QtGui.QIcon.Normal, QtGui.QIcon.Off)    mainWindow.setWindowIcon(icon)

 

完整测试：

左上角可以看到小图标，任务栏图标需要打包成exe才能看到

import sysfrom PyQt5 import QtCore, QtGui, QtWidgetsclass Ui_MainWindow(object):    def setupUi(self, MainWindow):        MainWindow.setObjectName("MainWindow")        MainWindow.resize(480, 318)        self.centralwidget = QtWidgets.QWidget(MainWindow)        self.centralwidget.setObjectName("centralwidget")        self.gridLayout = QtWidgets.QGridLayout(self.centralwidget)        self.gridLayout.setObjectName("gridLayout")        self.textBrowser = QtWidgets.QTextBrowser(self.centralwidget)        self.textBrowser.setObjectName("textBrowser")        self.gridLayout.addWidget(self.textBrowser, 1, 0, 1, 1)        self.pushButton = QtWidgets.QPushButton(self.centralwidget)        self.pushButton.setObjectName("pushButton")        self.gridLayout.addWidget(self.pushButton, 2, 6, 1, 1)        self.lineEdit = QtWidgets.QLineEdit(self.centralwidget)        self.lineEdit.setObjectName("lineEdit")        self.gridLayout.addWidget(self.lineEdit, 2, 0, 1, 1)        self.verticalLayout = QtWidgets.QVBoxLayout()        self.verticalLayout.setObjectName("verticalLayout")        spacerItem = QtWidgets.QSpacerItem(20, 30, QtWidgets.QSizePolicy.Minimum, QtWidgets.QSizePolicy.Expanding)        self.verticalLayout.addItem(spacerItem)        self.label = QtWidgets.QLabel(self.centralwidget)        self.label.setIndent(0)        self.label.setOpenExternalLinks(False)        self.label.setObjectName("label")        self.verticalLayout.addWidget(self.label)        spacerItem1 = QtWidgets.QSpacerItem(20, 20, QtWidgets.QSizePolicy.Minimum, QtWidgets.QSizePolicy.Expanding)        self.verticalLayout.addItem(spacerItem1)        self.gridLayout.addLayout(self.verticalLayout, 1, 6, 1, 1)        MainWindow.setCentralWidget(self.centralwidget)        self.menubar = QtWidgets.QMenuBar(MainWindow)        self.menubar.setGeometry(QtCore.QRect(0, 0, 480, 18))        self.menubar.setObjectName("menubar")        MainWindow.setMenuBar(self.menubar)        self.statusbar = QtWidgets.QStatusBar(MainWindow)        self.statusbar.setObjectName("statusbar")        MainWindow.setStatusBar(self.statusbar)        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", "发送"))        self.pushButton.setShortcut('enter')        self.label.setText(_translate("MainWindow", "小明"))if __name__ == '__main__':    # QtCore.QTextCodec.setCodecForCStrings(QtCore.QTextCodec.codecForName("utf-8"))    app = QtWidgets.QApplication(sys.argv)    mainWindow = QtWidgets.QMainWindow()    ui = Ui_MainWindow()  # 窗口类    ui.setupUi(mainWindow)    # 设置窗口图标    icon = QtGui.QIcon()    icon.addPixmap(QtGui.QPixmap("logo.ico"), QtGui.QIcon.Normal, QtGui.QIcon.Off)    mainWindow.setWindowIcon(icon)    mainWindow.show()    sys.exit(app.exec_())    passpass