Abstract: Heat sink in space environment simulation equipment is used to simulate space cold and black environment.We made a simulation study on the fluid distribution and temperature uniformity of plate-style heat sink,using nitrogen gas as refrigerant,studied the influence of wallboard distance and nitrogen gas pressure,velocity on fluid distribution.With the method of Computational Fluid Dynamics,the numerical simulation and analysis of the flow field are carried out,the influence of wallboard distance,nitrogen gas pressure and velocity on the temperature uniformity of heat sink is obtained.