第一步：装pyqt5和pyserial库

pip install pyqt5 pyserial

第二步：完整代码

import sys
from PyQt5.QtWidgets import QApplication, QMainWindow, QPushButton, QVBoxLayout, QWidget, QLabel, QComboBox, \
    QGridLayout, QLineEdit, QTextEdit
from PyQt5.QtCore import QIODevice
from PyQt5.QtSerialPort import QSerialPort, QSerialPortInfo


class SerialDebugHelper(QMainWindow):
    def __init__(self):
        super(SerialDebugHelper, self).__init__()

        self.serial = QSerialPort()
        self.serial_port_info_list = QSerialPortInfo.availablePorts()
        self.initUI()

    def initUI(self):
        self.setWindowTitle('串口调试助手')
        self.setGeometry(300, 300, 600, 400)

        layout = QGridLayout()

        self.port_label = QLabel('串口:')
        self.baudrate_label = QLabel('波特率:')
        self.port_combo_box = QComboBox()
        self.baudrate_combo_box = QComboBox()
        self.refresh_button = QPushButton('刷新')
        self.open_button = QPushButton('打开串口')
        self.close_button = QPushButton('关闭串口')
        self.send_button = QPushButton('发送')
        self.clear_button = QPushButton('清除')
        self.send_line_edit = QLineEdit()
        self.received_text_edit = QTextEdit()

        self.refresh_serial_ports()
        self.baudrate_combo_box.addItems(['300', '1200', '2400', '4800', '9600', '19200', '38400', '57600', '115200'])
        self.baudrate_combo_box.setCurrentText('9600')  # Default to 9600

        layout.addWidget(self.port_label, 0, 0)
        layout.addWidget(self.port_combo_box, 0, 1)
        layout.addWidget(self.baudrate_label, 1, 0)
        layout.addWidget(self.baudrate_combo_box, 1, 1)
        layout.addWidget(self.refresh_button, 0, 2)
        layout.addWidget(self.open_button, 1, 2)
        layout.addWidget(self.close_button, 1, 3)
        layout.addWidget(self.received_text_edit, 2, 0, 1, 4)
        layout.addWidget(self.send_line_edit, 3, 0, 1, 3)
        layout.addWidget(self.send_button, 3, 3)
        layout.addWidget(self.clear_button, 4, 3)

        self.refresh_button.clicked.connect(self.refresh_serial_ports)
        self.open_button.clicked.connect(self.open_serial_port)
        self.close_button.clicked.connect(self.close_serial_port)
        self.send_button.clicked.connect(self.send_data)
        self.clear_button.clicked.connect(self.clear_received_data)

        central_widget = QWidget()
        central_widget.setLayout(layout)
        self.setCentralWidget(central_widget)

    def refresh_serial_ports(self):
        self.port_combo_box.clear()
        self.serial_port_info_list = QSerialPortInfo.availablePorts()
        for port in self.serial_port_info_list:
            self.port_combo_box.addItem(port.portName())

    def send_data(self):
        if self.serial.isOpen():
            data = self.send_line_edit.text().encode()
            self.serial.write(data)
            self.send_line_edit.clear()

    def clear_received_data(self):
        self.received_text_edit.clear()

    def on_serial_read(self):
        bytes_to_read = self.serial.bytesAvailable()
        text = self.serial.read(bytes_to_read).decode()
        self.received_text_edit.insertPlainText(text)

    def open_serial_port(self):
        port_name = self.port_combo_box.currentText()
        baud_rate = int(self.baudrate_combo_box.currentText())
        self.serial.setPortName(port_name)
        self.serial.setBaudRate(baud_rate)
        self.serial.setDataBits(QSerialPort.Data8)
        self.serial.setParity(QSerialPort.NoParity)
        self.serial.setStopBits(QSerialPort.OneStop)
        self.serial.setFlowControl(QSerialPort.NoFlowControl)
        if self.serial.open(QIODevice.ReadWrite):
            self.serial.readyRead.connect(self.on_serial_read)
            self.open_button.setEnabled(False)
            self.close_button.setEnabled(True)

    def close_serial_port(self):
        if self.serial.isOpen():
            self.serial.close()
            self.open_button.setEnabled(True)
            self.close_button.setEnabled(False)

    def closeEvent(self, event):
        self.close_serial_port()
        event.accept()


if __name__ == "__main__":
    app = QApplication(sys.argv)
    mainWin = SerialDebugHelper()
    mainWin.show()
    sys.exit(app.exec_())

第三步：运行结果

你可以用单片机或含串口的外设去测试，也可以下一个虚拟串口，附上网盘链接如下：

链接：https://pan.baidu.com/s/1V6w7vNGvMen6tspPJQcKiw 
提取码：1bss 
然后选择添加虚拟串口1、串口2，并且用一个现成的串口调试助手去测试；在你运行的串口助手选择串口号1，现成的串口调试助手选择串口2，并且二者波特率选择一致，就可以互相通讯了。