A thermal simulation model of 5 A emission current hollow cathode was established by using finite element method, and the model verification and temperature analysis under typical working condition were investigated. The results show that the model can better reflect the energy transmission process inside the hollow cathode. The comparison error between the simulation results and the test results is less than 5%. The temperature difference of hollow cathode is mainly caused by heating current. The ambient temperature mainly affect the external components of hollow cathode, and the high ambient temperature under the influence of solar irradiation is more conducive to the start-up of the thruster. When the hollow cathode is heated and in self-sustaining discharge state, the temperature of the emitter reaches 2 122 ℃ and 2 126 ℃ at the ambient temperatures of 0 ℃ and 94 ℃, respectively, which is close to the temperature resistance limit of the emitter. Therefore, the hollow cathode must avoid the extreme condition.