说明：此文章主要为了记录在界面文本显示区域，实时显示最新数据，及将滚动条固定在最下方。

代码复制可用。

import sys
from PyQt5 import QtWidgets, QtGui, QtCore


class ClassTextAreaWrite(QtWidgets.QWidget):

    def __init__(self):
        super(ClassTextAreaWrite, self).__init__()
        self.init_ui()
        self.bind_trigger()

    def init_ui(self):
        self.setGeometry(300, 300, 300, 220)
        self.setWindowTitle("PushButtonClicked")
        button = QtWidgets.QPushButton(text="Start", parent=self)
        self.button = button
        timer = QtCore.QTimer()
        self.timer = timer

        view_area = QtWidgets.QPlainTextEdit(parent=self)
        view_area.setGeometry(10, 60, 280, 100)
        self.view_area = view_area

    def write(self, text):
        """"""
        cursor = self.view_area.textCursor()
        cursor.movePosition(QtGui.QTextCursor.End)
        cursor.insertText(text + "\n")
        self.view_area.setTextCursor(cursor)
        self.view_area.ensureCursorVisible()

    def bind_trigger(self):
        # Button clicked trigger
        self.button.clicked.connect(lambda: self.timer.start(1))
        self.timer.timeout.connect(self.clicked_button)

    def clicked_button(self):
        self.write("Write Num: {0}".format(self.timer.interval()))
        self.timer.setInterval(self.timer.interval() + 1)


if __name__ == '__main__':
    app = QtWidgets.QApplication(sys.argv)
    push_button_clicked = ClassTextAreaWrite()
    push_button_clicked.show()
    sys.exit(app.exec_())

Tips: 在PyQt中使用time.sleep(1)会导致界面阻塞。所以此处使用了QTimer，更多详细内容请见专栏QTimer文章。