Abstract: The influences of inertia effect and face tilt on steady performance and dynamic characteristics of super high-speed gas face seal were investigated. The steady-state and dynamic numerical analysis model of gas face seal were established with considering gas inertia effect. Steady and perturbation Reynolds equation were solved utilizing finite difference method, and pressure distribution was obtained. The influences of inertia effect and face tilt on steady performance, including opening force, film stiffness and gas leakage, and dynamic characteristics, including stiffness and damping coefficient, of gas face seal were analyzed numerically. Furthermore, the optimal geometrical parameters of spiral groove of gas face seal were obtained for large stiffness coefficient. Results showed that inertia effect would significantly decrease leakage and significantly increase stiffness-leakage ratio at the super high-speed, while the opening force, film stiffness and dynamic characteristic coefficient changed little. There were better dynamic stiffness and damping characteristics at high and low frequencies with considering inertia effect and face tilt.