Abstract With the development of the miniaturization and the high integration of electronic chip, the thermal management of the high power electronic becomes a major challenge. In this paper the influence of heat sink temperature on operational characteristics was comprehensively conducted and the 35% of charging ratio was selected through the experiment study. To evaluate the LHP system, temperatures, start-up time, thermal resistance, and evaporator heat transfer coefficient were selected as performance indicators. The result showed that, there existed an optimal heat sink temperature (18°C) to obtain the lowest evaporator bottom temperature (77°C), the shortest start-up time (1000s), the smallest thermal resistance (0.29k/W), and the highest evaporator heat transfer coefficient (3.1 × 104 W/(m2·k)). The temperature range to keep a high performance of LHP system was 14-20°C. The conclusion obtained through the experiment can provide the reference of design the cooling system when the LHP system applied into the electric cooling.