Abstract: The metal particle on the insulator surface is an important cause of GIS insulator failure. In field operation, the insulators work is not only under electric stress, but also under temperature gradient. Therefore, it is of great significance to study the partial discharge (PD) and flashover characteristics of insulator surface defects under electrothermal coupling effect. In this paper, the electrothermal coupling experiment platform was established to study the PD and flashover characteristics of metal particles on the insulator surface under different temperature. The results show that when the maximum temperature of the insulator increases from 25℃ to 75℃, the PD inception voltage (PDIV) of metal particles decreases by about 16%, and the average and maximum apparent charge of PDs increased from 0.55pC and 9.1pC to 1.45pC and 11.5pC respectively, while the discharge repetition rate also increases from less than 200 times/s to nearly 400 times/s. However, the temperature has little effect on the flashover voltage. This paper is helpful to understand the influence of temperature on the PD and flashover characteristics of metal particle defects on insulator surface under electrothermal coupling effect.