Abstract: Monitoring partial discharge of GIS and determining the location of partial discharge source are important means to prevent insulation accidents. Aiming at the problems of high cost and difficult wiring in current positioning methods, a GIS partial discharge signal monitoring device and localization method is proposed based on UHF sensor. The abnormal electromagnetic signals are sensed by the UHF sensors which are deployed in the GIS body and surrounding space. The UHF cumulative average signal strength and characteristic similarity are used to eliminate spatial interference signals and identify partial discharge signals in GIS. Combined with the spatial topological relationship between sensor and GIS, the position of PD source can be judged according to the signal intensity of UHF. Through field application, the location of PD source is accurately located, which proves the feasibility of the location method.