import serial

import serial.tools.list_ports

port_list = list(serial.tools.list_ports.comports())

port_list_name = []

if len(port_list) <= 0:

    print "The Serial port can't find!"

else:

    for each_port in port_list:

        port_list_name.append(each_port[0])

if __name__ == '__main__':

    print port_list_name

[u'COM3', u'COM1', u'COM2', u'COM4']