Abstract: Direct torque control strategy of permanent magnet synchronous motor based on speed-sensorless technology was studied, and space vector pulse width modulation technique was applied in switching sequence selection of voltage source inverter. Delay of the pulse width modulation was eliminated through controlling of flux and torque by hysteresis controller, and harmonic suppression of voltage and current were achieved by use of low-pass filter. The simulation results show that actual speed of motor is similar to predicted speed under different torque responses after appling the strategy, the time needed by the motor to accelerate to desired reference time is very short, and the tracking is also good.