Abstract: In the current research on air foil bearings, the flat foil is simplified by the beam model and the coupling relationship of the flat foil deformation in the axial direction is neglected, resulting in limited calculation accuracy. A mechanical model of air foil bearing based on thin plate bending theory and considering the comprehensive elastic deformation of flat foil is established, which realizes more accurate calculation of foil deformation and force. Combined with the Reynolds equation, a fluid-solid coupling algorithm that can calculate the mechanical properties and lubrication performance of air foil bearings is constructed. Through the actual test, the test and calculated values of eccentricity and friction torque are compared, and the reliability of the established calculation model is verified. On these bases, combined with a set of example parameters, the performance of air foil bearings is studied in depth. The influences of speed and load on bearing performance parameters are obtained. The influences of bearing structure parameters such as flat foil thickness, bump foil thickness, bump arch height and half length of bump on the performance of air foil bearing are studied.