In order to measure transient overvoltage signal of power system GIS online, a device based on Zinc Oxide valve partial pressure extraction transient overvoltage signal is developed. First, the basic principle of the technology is introduced. Secondly, the simulation circuit is built by ATP-EMTP, and the voltage divider circuit of Zinc Oxide valve is set up. The experiment is carried out under transient overvoltage, operating overvoltage and lightning overvoltage. The results show that the partial pressure ratio of the valve plate under transient overvoltage, operation overvoltage and lightning overvoltage Under constant current, the overshoot and oscillation of the wave head occur under lightning overvoltage. Finally, the Zinc Oxide lightning arrester scavenging experiment is carried out. The results show that the frequency characteristics of the Zinc Oxide arrester in 1.5MHz are basically unchanged, and the practicability of the simulation is verified. This measurement technology is of great significance to the fault analysis of power system and the establishment of insulation tolerance experiment standard for power equipment.