from PyQt5 import QtCore, QtWidgets
if __name__ == "__main__":
import sys
app = QtWidgets.QApplication(sys.argv)
date_str = "1-Jan-2020"
# convert str to QDate
qdate = QtCore.QDate.fromString(date_str, "d-MMM-yyyy")
widget_date = QtWidgets.QDateEdit()
# Set the format of how the QDate will be displayed in the widget
widget_date.setDisplayFormat("d-MMM-yyyy")
widget_date.setDate(qdate)
widget_date.show()
sys.exit(app.exec_())