In view of the vector control of motor parameter dependent problems, based on the relevant theory of the existing mathematical model of permanent magnet synchronous motor and direct torque control, synchronous reluctance motor mathematical analysis, the direct torque control method of synchronous reluctance motor was proposed. It includes the calculation of space voltage vector, hysteresis control of flux linkage and torque, etc. based on the estimation of position information, a PI controller with integral separation was introduced, and a closed-loop controller of speed was designed. The simulation model of the system was built, and the steadystate and dynamic performances of the motor were simulated and analyzed. The result showed that the system designed based on this method could change speed at a wide speed range.