Taking the derived spiral groove as research object,a three-dimensional flow model of micro gas film in the end face of derived spiral groove was established.The physical parameters of CO2 under different pressure and temperature were obtained by software REFPROP,and the film pressure distribution of derived spiral groove and classic spiral groove was obtained by Fluent.The opening force,leakage rate and film stiffness of S-CO2 dry gas seal with derived spiral groove and classic spiral groove were analyzed.The influence of actual gas effect,centrifugal inertia force effect and turbulence effect on the steady-state performance of seal under different inlet pressure and speed was discussed.The sealing mechanism of interaction coupling of various effects on the dynamic characteristics of S-CO2 dry gas seal film was analyzed.The results show that the performance parameters such as opening force,leakage rate and film stiffness of the derived spiral groove are improved compared with the classical spiral groove,which is the result of the two-step action of the derived spiral groove.With the increase of rotating speed,the opening force,leakage rate and film stiffness first increase and then decrease under the mutual coupling of turbulence effect and centrifugal inertia force.With the increase of inlet pressure,the opening force,leakage rate and gas film stiffness increase approximately linearly,and the difference between derived spiral groove and classical spiral groove becomes more and more obvious with the increase of pressure.