In this research, the membrane separation process was used to separate helium from methane gas. In order to do this, computational fluid dynamics (CFD) was used, and the effect of process parameters on the performance of the membrane separation process was studied by this method. To simulate the hydrodynamics of flow in the channel, the Navier-Stokes equation was used, and the Maxwell-Stefan equation was applied to simulate the mass transfer phenomenon. In addition, Fick's law was utilized to simulate mass transfer in the membrane domain. The impacts of significant parameters such as feed pressure, feed flow rate, and feed concentration on parameters such as He/CH 4 separation factor, methane and helium membrane flux and helium mole fraction in permeate stream were studied. The results of the simulation indicated that the feed pressure of 10 bar, feed flow rate of 120 cm 3 min -1 , and feed mole fraction of 0.0254 had the best membrane performance in He/CH 4 separation.