Abstract: Scheme of pumped two-phase loop with micro-channel evaporator，phase change device and radiator was brought forward to solve the thermal control problem of high power source applied to spacecraft in the future.Simulation was conducted to research characteristics and thermal control capability of two-phase loop with Sinda/Fluint thermal analysis software.The results are consistent with prediction，and temperature of the heat sources is under control.The conclusion is drawn that excessive drive capacity of pump results in bigger temperature difference of two-phase loop by simulation.Effect of heat transfer capacity of evaporator and phase change device on thermal control system was analyzed and suggestions were given.

Key words: high power source, twophase loop, system simulation, excess drive capacity, heat transfer performance