Take-off speed is an important performance index of air bearing.Taking spiral groove air bearings as the research object,perturbation method was used to solve the differential equation of pressure distribution of spiral groove gas lubricated bearings under isothermal compressible conditions,and the pressure distribution and bearing capacity of air bearings were obtained.Aiming at the maximum bearing capacity,the structural parameters of the spiral groove air bearing were calculated,and the designed air bearing was tested to explore its take-off velocity under different loads.The test results show that,under no-load condition,when the rotating speed is about 1 200 r/min,the rotor of the air bearing is out of contact with the bearing sleeve and the take-off speed is reached.The take-off speed and take-off torque both increase gradually with the increase of load,and the bearing capacity also increases with the increase of rotating speed.It is proved that the designed spiral groove air bearing has good performance,which provides the theoretical and practical basis for the subsequent design optimization and practical application of spiral groove bearing.