Abstract: Based on the principles of dynamic gas seal and hydrostatic gas seal, a new kind of gas seal, namely dynamic-hydrostatic hybrid gas seal(DHHGS), was proposed. Gas film pressure distribution between the two faces of dynamic seal, hydrostatic seal and DHHGS were obtained by solving the Reynolds equation of the gas film numerically. The sealing performance parameters, i.e. opening force, steady-state stiffness, leakage rate and frictional power were evaluated. Operating characteristics of DHHGS were investigated by comparing the sealing performances of different structure of seal end faces of DHHGS, hydrostatic seal and dynamic seal. Specifically sealing performances of DHHGS and hydrostatic seal without initial gas pressure were analyzed. Results showed that the opening force of DHHGS was larger in the same gas film thickness and the stiffness of DHHGS was still greater when the gas film thickness increased, compared with dynamic seal. Static opening and dynamic running could be well achieved with DHHGS. As it has both the hydrodynamic effect and hydrostatic effect simultaneously, DHHGS could find more applications in engineering. In addition the sealing performance, parameters of DHHGS could be changed through gas source pressure adjustment online.