The invention provides a partial discharge locating method and system of a switch cabinet. The partial discharge locating method of the switch cabinet includes the following steps of arranging multiple ultrasonic sensors used for monitoring discharge capacity of discharge points within one locating plane, wherein the discharge points are positioned within the locating plane; according to the discharge capacity received by each ultrasonic sensor, calculating the corresponding discharge distance between each sensor and the corresponding discharge point; with each ultrasonic sensor as a circle center and the corresponding discharge distance obtained by means of calculation as the radius, obtaining a locating circle of each ultrasonic sensor; according to the intersected areas of the locatingcircles of the ultrasonic sensors, obtaining the positions of the discharge points. The partial discharge locating method has the advantages that the partial discharge locating method of the switch cabinet is based on a plane locating principle of the ultrasonic sensors, and the positions of the discharge points can be located conveniently, quickly and accurately. The invention also provides the partial discharge locating system of the switch cabinet.