Abstract: The paper introduced basic principle, detection and determinants of partial discharge detection method based on a combination method of ultrasound and high-frequency current. The detection method was applied to partial discharge detection of a high-voltage power distribution room of 35 kV switchgear and the result verified the method can accurately determine partial discharge position, discharge phase, type of discharge and discharge intensity of switchgear, and can analyze its tendency, which provides a strong technical support for online monitoring of switchgear status.