Insulator is exposed to air for a long time, which may cause pollution flashover and threaten the safety and reliability of power grid. Based on the method of laser cleaning insulator contamination, the finite element simulation model of laser cleaning insulator contamination is established. The distribution of temperature field in the process of laser cleaning insulator contamination is studied. The central point of laser spot has the highest temperature and the maximum temperature of the contamination surface reaches 473 K when the average power density of the laser is 200 W/cm2. The temperature around the spot and in the depth direction decays rapidly. The calculation results show that the temperature increases linearly with the increase of power density and decreases with the increase of scanning rate. The maximum temperature of the substrate surface in the cleaning process is analyzed and it is considered that there is no thermal damage to ceramic insulator. Finally, laser cleaning experiment was carried out. The experimental results show that the laser cleaning can effectively remove the dirty layer and will not damage the substrate material. The maximum temperature in the cleaning process is slightly lower than the simulation results, and the error is within 8%.