The zinc oxide surge arrester is an important barrier to protect the power system from lightning, and maintaining its good thermal stability is of great significance for its safe operation. In this paper, the model of lightning arrester is established by finite element, the simulation calculation of the electrical-thermal characteristics under the impact of lightning current and large current is studied, the heating and heat dissipation characteristics of the arrester under different conditions are obtained, and the arrester is found in different environments Maximum operating temperature at temperature. And through the joint pressurization test, the temperature of the resistor sheet when the arrester thermally collapses under actual conditions is found, and the test results are in agreement with the simulation results. The research results show that if the zinc oxide resistor has a large amount of heat, poor heat dissipation from the resistor, and uneven electric field distribution, the arrester will reach the limit operating temperature. When the limit temperature is exceeded, the arrester will soon fall into thermal collapse and thermal fusion will occur. Wear, crack, and explode. Therefore, effective measures must be taken to improve the thermal stability of zinc oxide surge arresters.