Abstract: The function of thermal management system for lunar rover is to ensure the temperature in an appropriate range, and, at the same time, within a mass constraint. By analyzing the thermal network of the system, several essential factors affecting the system weight are computed, such as the exit temperature of the radiator, the tube diameter of the thermal loop, the mass of the cooling-fluid, as well as the electronic control components, the tube design and the valve usages, to determine their influencing laws to the system weight. Based on that, the searching for the optimal structural and operation parameters of the rover system is implemented according to the environment parameters and working parameters of the lunar rover model. The optimized parameters are obtained for light weight purpose. Thus the principal analysis of mass optimization of the thermal management system are realized, with some reference value for engineering applications.