Abstract: A kinetic model of hybrid gas-lubricated bearing-rotor system is established based on gas lubrication theory and rotor dynamics, and the time-varying characteristics of its nonlinear damping are further clarified. Moreover, the compressibility of the gas film is presented by separating radial and axial forces from the supporting gas film based on Semi-Sommerfeld condition, which could provide an important supplement to previous dynamic model of this system. Finally, the stability indexes, such as response time, critical velocity, radial runout, and axis trajectory of the system under different static pressure and speed are systematically studied by experiments and visual measure methods. The results demonstrate that there is a significant variation in the compressibility of gas film at different position around the spindle rotation, leading to nonlinearity in damping and stiffness within the hybrid gas-lubricated bearing-rotor system. By corresponding static pressure supplement, the dynamic stiffness and damping characteristics can be improved according to the working condition. Specifically, the spindle response time can be reduced to 31.2% ~ 66.0%, and spindle radial runout can be reduced to 35.6% ~ 41.9% as well. Furthermore, critical speed can be increased up to 1.5 ~ 1.8 times for improved rotor performance.