To improve the performance of permanent magnet synchronous motor drive system, a speedsensorless deadbeat direct torque control (DBDTC) of interior permanent magnet synchronous motor (IPMSM) was presented. Based on the discrete model of the motor, the deadbeat voltage control law of the torque and flux linkage was derived. By employing a graphical analysis method, the physical meanings of the voltage vector solution were explained clearly. The speed sensorless control of IPMSM was realized by combining the DBDTC and the speed estimation method which based on the active flux observer. Simulation results verified the effectiveness of the proposed method.