As the core equipment of power system, GIS has frequent faults in the current operation process. In order to ensure the safe operation of power system, it is necessary to monitor the operation status of GIS equipment in real time. However, due to the unreasonable distribution of on-site UHF on-line monitoring sensors, it is difficult for the UHF on-line monitoring device to receive effective partial discharge signals, which affects the early warning effect of the device on GIS discharge faults. In this paper, through the actual investigation of the distribution of UHF sensors on site, the important influencing factors of the effectiveness of sensor distribution are obtained, and the distribution principle of UHF sensors on site is proposed, which is of great research significance for improving the effectiveness of UHF online monitoring devices.