A ultrasonic levitation support structure for axialsupport motor rotor is designed in this paper. The conetype bearing suspended support structure was used and the hosted capacity was analyzed and tested. The relationship between the suspension force and the suspension clearance has been obtained. The hosted gas film was formed in the vibration process. The effect of the suspension clearance change on the critical speed and vibration mode of the motor rotor was analyzed theoretically. The experimental study on the relationship between the maximum speed of revolution and the suspension clearance was carried out. The results have shown that the stiffness support effect of the gas film can be enhanced by reducing the suspension clearance and increase the maximum speed of revolution.