In order to further improve the stability of small orifice throttle gas bearing,the dynamic characteristics of small orifice throttle gas bearing with spiral groove were studied.The dynamic Reynolds equation under the unsteady working condition was established,and the dynamic characteristic coefficient was solved by partial derivative integral method.The influence of spiral groove,vortex ratio,rotational speed,air supply pressure,groove width and groove depth on the dynamic characteristics of the bearing was studied.The results show that the spiral groove can significantly improve the dynamic characteristics of the bearing and can increase the stability of the bearing.The direct stiffness coefficients increase and the cross stiffness coefficients and the damping coefficients decrease with the increase of the vortex ratio.With the increase of the rotational speed,the stiffness coefficients increase and the damping coefficients decrease.With the increase of the air supply pressure,the stiffness and damping coefficients increase.With the increase of the groove width,the direct stiffness and damping first increase and then decrease,and the cross stiffness and damping have little change.With the increase of the groove depth,the direct stiffness increases,and the cross stiffness and damping coefficients first increase and then decrease.