Abstract: The heat sink is an important subsystem of the space environment simulator. This paper described the key structural factors including the main pipe of heat sink、branch pipe、pipe spacing and other factors, which was how to affect the heat sink flow field uniformity of nitrogen gas. Research method was numerical simulation,with mature finite element analysis software on the computer (ANSYS)to realize simulated calculation of the process. The FLUENT calculation module was used to calculate,and the model of calculation was K-#model. Through simulated calculation,the aim was to get the key structure factors on nitrogen gas flow field uniformity of heat sink. Using these rules,we can provide the reference for the heat sink structures design,and also make contribution to develop the superior performance of the space environment simulator.