Aerostatic bearings have been applied widely in aviation, aerospace and precision electronics. Three-axis table is the equipment that has high precision and is used to check, demarcate and establish the error model of inertial system and work-piece. The measurement accuracy is related to the control and navigation in aviation and aerospace school. The equipment’s accuracy has influence on the revolution accuracy. Porous aerostatic bearings have higher load capacity, static stiffness and highed damping than other restricted bearings. The paper presents theoretical analysis of porous aerostatic bearings and compares them with orifice aerostatic bearings. The results show the load capacity of porous aerostatic bearings is higher than orifice aerostatic bearings.