In order to research the transientstate flow field characteristics of spherical spiral groove aerodynamic bearings,3D micro gas film mathematical model of the gas bearings was established,and 3D gas film pressure field of the bearings was analyzed based on the FLUENT software of fluid dynamics to obtain the bearing structure parameters and operation parameters at the maximum bearing capacity.The effects of different speeds and eccentricity ratio on dynamic characteristic coefficients were studied at the maximum bearing capacity,and the transient nonlinear dynamic behavior of the gas bearings was explored.The axis orbit of the bearings at different speeds was simulated and the stability of bearings was researched.The results show that the bearing characteristics of the bearings are obviously influenced by the groove width ratio,groove depth ratio and eccentricity ratio. It is helpful to improving the stability of bearings by increasing the speed and eccentricity,but with the increasing of rotational speed,the stability of rotor bearing system is close to critical state,which will lead to instability of rotor bearing system.While larger eccentricity is easy to cause the phenomenon of rub,which will also destroy the stability of the bearing.Therefore,in the process of bearing design,the rational parameters of the bearings should be chosen to improve the comprehensive performance of bearings.