A vacuum preloaded circular aerostatic bearing was designed and its static characteristics were investigated experimentally. The load carrying capacity and air film thickness of the bearing were measured for different air supply pressure and vacuum pressure values. An orthogonal table was constructed to optimize the experimental measurement. Regression analysis was performed on the experimental results to obtain an analytical model of the bearing stiffness as a function of the load carrying capacity, air supply pressure and vacuum pressure. Accuracy of this analytical model in predicting static characteristics of the aerostatic bearing was validated by comparison with experimental data, and influences of the functioning parameters were also discussed.