In view of the flaw of large flux linkage and torque ripple found in the traditional direct torque control system of permanent magnet synchronous motor (PMSM), which makes it difficult to control accurately at low speed, and the defect of weak adaptability of PI controller to parameters, an effective flux sliding mode algorithm is adopted to improve the performance of PMSM. Taking the stator current and effective flux taken as state variables, the stator flux can be derived from the effective flux, with the fuzzy PI controller used to replace the traditional PI controller to optimize the traditional direct torque control. The simulation results show that the proposed control method is characterized with a strong adaptability and robustness.