Proposes a flux weakening control strategy based on current boundary limit condition by analyzing the characteristics of the current limiting circle and voltage limiting circle and the practical application of variable frequency driving of motor, under the Space Vector Pulse Width Modulation (SVPWM) control strategy. This method can make the output torque current close to the torque current constraints condition and then the stator current vector close to the current limiting circle, after adjusting exciting current. Compared with the voltage closed-loop flux weakening control method, this method can make the biggest exciting current as the exciting current initial value, improved the torque output capacity in the constant torque region. In the flux weakening region, it is not necessary to consider the problem of voltage margin, which can make full use of the voltage output and improve the output capability of the torque of the flux weakening region. In view of the non-linearity of the exciting current regulation process, the fuzzy PI controller was introduced, which makes the regulation process more precise and has better dynamic and static characteristics.