In order to obtain good performance of spiral groove dry gas seal, Reynolds equation and film thickness governing equation are solved by finite difference method based on gas film lubrication theory, and the pressure distribution law of gas film lubrication is obtained. With opening force and leakage rate as evaluation indexes, the effects of rotating ring speed, spiral groove number and spiral groove depth on the gas film lubrication performance of dry gas seal are compared and analyzed, and the calculation model and parameter range with lubrication characteristics are obtained. The results show that the steady-state performance parameters of the dry gas seal are increased with the increase of the rotating ring speed, but the deformation and pressure distribution of the gas film are little effect. When the number of spiral grooves are 12~16 and the depth of spiral grooves is 4.5~6.5 μm, the dynamic pressure effect caused by pressure gradient is obvious, and good sealing effect can be achieved.