In order to improve the drift accuracy of aerostatic bearings, the air supply pressure and manufacturing errors effect on vortex torque of aerostatic bearings were studied by using the finite element method. This paper analyzed the influence of air supply pressure on vortex torque, in view of elliptical error, incline error of throttle slit and radial eccentricity ratio exist. The quadratic regression orthogonal design was adopted to establish function expression of vortex torque among air supply pressure, elliptical error, incline error of throttle slit and radial eccentricity ratio. In research, the simulation vortex torque values of a certain aerostatic bearing are compared with the experimental values. The predicted characteristics are in good agreement with experimental results and then prove that the finite element model, the method used to solve the problem and the function expression obtained are correct. The research has great significance for predicting performance and choosing the air supply pressure of aerostatic bearings.