Abstract: In order to solve the problem of gas dynamic seal and vibration of rotor system in high-speed rotating machinery, a novel gas film seal damper (GFSD) with flexible metal rubber ring was brought forward. The function of gas film between the stator and rotor is seal and damping while the high elasticity ring can control the dynamic property of gas film. The quasi-static method was employed to describe the fluid-solid coupling among rotor, gas film and metal rubber ring. Based on finite difference method, the gas film pressure field was analyzed, and the effects of the structural and working parameters on the stability performance of GFSD, including gas film force, leakage and friction torque, were discussed. The results show that the flexible ring can improve gas film pressure field effectively. The proper range of structural parameters is defined by the actual working conditions. With the given working parameters, a better stability property will obtain with the ratio of width and diameter 1.5, the seal clearance 0.05mm and the flexible coefficient around 2.