The invention discloses a multi-channel ultrasonic detection-based gas insulated switchgear fault source location method. A plurality of ultrasonic detection units are mounted on the housing of a GIS (gas insulated switchgear) to be detected according to a certain rule to monitor ultrasonic signals during a voltage-withstanding test or equipment operation, and a wireless transmission module is then utilized to transmit a measurement result to a background system in a safe area. When the equipment generates an abnormal signal or breakdown takes place, the multi-channel ultrasonic signal is analyzed and processed, so that the position with the abnormal ultrasonic signal or the faulty breakdown point can be accurately located within 50cm. the system does not change the original wiring and operation mode of the GIS, and is convenient to install and operate, and the fault source location effect is remarkable.