The anti-theft extension module is designed to provide real-time operation detection and alarm of the power supply cable for outdoor street lamps. It is generally installed in the distribution cabinet. The street lamp cable remote monitoring is realized through the street lamp management cloud platform. When the power supply cable is stolen, it will be issued as soon as possible. The alarm signal informs the monitoring center and related management personnel to make corresponding treatments to achieve effective anti-theft protection for the 6 street lamp circuits 24 hours a day. It has the characteristics of strong adaptability, low false alarm rate, convenient installation and maintenance, and long service life. It is a cost-effective anti-theft device for efficiently protecting terminal cables.