Soft ferrite has the characteristics of high permeability, high resistivity, low loss. Based on this, a new flux-weakening structure of high-speed permanent magnet motor was presented. The structure relies on changing the saturation of soft magnetic ferrite to change the equivalent magnetic resistance of permanent magnet magnetic circuit in the motor, so the main flux of the permanent magnet motor can be reduced. By the 3D Finite Element analyses, the magnetic field distribution characters in the air gap can be pointed out. The analysis results prove the flux-weakening method is presented in this paper is correct and feasible. It can provide a practical flux-weakening method of the high-speed PM motor.