Abstract: With the discovery of permanent magnet materials and the continuous development of modern motor control technology,the control mode of three-phase permanent magnet synchronous motors has gradually evolved into two schools:vector control and direct torque control and either has its own advantages and disadvantages. Although there are differences between the two control modes in control system composition,control process,form and effect,both control modes have the same theoretical basis,and their nature is the same. It is verified by Matlab/Simulink software simulation and torque formula analysis.