The independence of the computational meshes is very important when numerically simulating the dry gas seal performance.The effect of mesh layers on the numerical simulation results of dry gas seal was studied with a spiral groove dry gas seal as an example.By ensuring the orthogonal quality and choosing same mesh density of gas film surface,the relative changed rates of opening force and mass leakage were selected as the reference parameters in mesh independence test,and the effects of mesh layers on the numerical simulation results were investigated by increasing the mesh layers of gas film thickness in the spiral groove and nongroove region respectively.The results show that when the groove depth is between 5 to 9 μm and the gas film thickness of nongroove region is between 1 to 6 μm,the effect of mesh layers of nongroove region on the numerical simulation results is significantly greater than that of the mesh layers of groove region.The mesh of film thickness is 1 layer per micron in the spiral groove and the corresponding mesh layers of film thickness are 7,8 and 10 in the nongroove region,the relative changed rates of opening force and mass leakage are all below 2%,1% and 0.5% respectively.