Aiming to effectively reduce the friction caused by the contact between the rotor and the stator, the ultrasonic extrusion bearing was proposed to apply in a smallscale rotor system, and the dynamic characteristics of the bearingrotor system were studied. The mode shape and frequency of the piezoelectric transducer′s optimal operation were determined by using ANSYS. The Reynolds equations for gasextrusion membranes were deduced and solved by the finite difference method. The effects of suspension gap and ultrasonic amplitude on the dynamic characteristics of the bearingrotor system were studied, which were validated by experimental test. The results show that the bearing can achieve stable operation and works better at the resonant frequency of the piezoelectric transducer.