With the help of the CFD software Ansys flotran,the threedimensional model of micro orifice array aerostatic radical bearings with different structure was set up.The effects on the static characteristics of aerostatic radial bearings were studied by the number and diameter of the micro orifice,the average radius clearance,and the axial location of restrictor.The results show that the bearing capacity and stiffness of the bearings are significantly increased with the increasing of the number of micro orifice within a certain range.At given average radius clearance,the bearing capacity and stiffness can be increased by reducing the diameter of micro orifice.There exits the best average radius clearance to make the bearing capacity the largest,while the stiffness of the bearing is decreased along with the increasing of the average radius clearance.There exits the best axial position of restrictor to make the bearing capacity and stiffness of the bearing the largest.The simulation results can serve to implement the structure optimization of aerostatic radial bearing. 