Abstract: A novel bar-type piezoelectric motor is proposed and its working principle is described. The mechanics equations of any meshing teeth at different positions on the internal profile of the fixed rigid gear are deduced. The force changes applied to the movable teeth by the flexible ring, the rotor and the rigid gear are investigated. The deformation and stress equations of the meshing tooth under the forces from the flexible ring, the rotor and the rigid gear are derived on the basis of the space semi-infinite body elastic theory. Changes of forces and stress along with the system parameters are analyzed. The research results could be used for the load-carrying capability and dynamics analysis of the motor.