The research of small hole throttle aerostatic bearing commonly uses the numerical analysis method to solve the simplified NavierStokes equation,which can not reflect the actual characteristics of the orifice exit flow field.The flow field characteristics of small orifice air static pressure thrust bearing were studied,and the small orifice air static pressure bearing model was set up.By using fluid analysis software to solve the full NavierStokes equations and using the turbulence model,the more accurate calculation results were obtained.The calculation results show that the pressure drops rapidly and negative pressure may occur after the gas flow out of the throttle orifice,and the value of pressure drop is proportional to the gas film clearance.Near the orifice exit,the air flow rate of the gas film upper and lower boundary is less than that of the gas film middle,and the gas is easy to be separated from the gas film upper boundary.