The invention discloses a detection method and a device for partial discharge of a mobile transformer, comprising a detection host. The detection host is connected with a high frequency current sensor, a ultrasonic sensor and an ultrahigh frequency sensor. The ultrahigh frequency sensor is arranged at an oil discharge valve of the transformer to detect partial discharge of the transformer, detection frequency band of the ultrahigh frequency sensor is 500 MHz-1500 MHz; the ultrasonic sensor is arranged on surface of a shell of the transformer through adhesive to detect partial discharge of thetransformer, the detection frequency band of the ultrasonic sensor is 20 KHz-100 KHz; a core or clip lead of the transformer passes through center of the high frequency current sensor, according to Faraday's law of electromagnetic induction, varying electric fields generate varying magnetic fields, so that the high frequency current sensor can acquire local discharge signals. According to the detection method and the device for the partial discharge of the mobile transformer, detection technology such as ultrahigh frequency, ultrasonic wave, high frequency current and the like are adopted, thedevice can movably detect on site, detection efficiency of the partial discharge of mobile transformer is obviously improved.