The invention provides a method and device for obtaining time delay of a control system of a permanent magnet motor. The method includes the steps that the tested motor is controlled to operate at constant rotating speed under an idle condition; a d-axis voltage instruction of the tested motor is input into an angle compensation PI adjustor of the control system of the motor to control the angle compensation PI adjustor to generate a delay compensation angle; the delay compensation angle is utilized for correcting a d-axis voltage instruction and a q-axis voltage instruction output by a current control PI adjustor; when the d-axis voltage instruction output by the current control PI adjustor is corrected to be zero, the delay time of the control system of the motor is calculated accordingto the mechanical angular speed of the tested motor and the present corresponding delay compensation angle. Influences of non-ideal factors of the control system of the motor are considered, and the delay time of the control system of the permanent magnet motor can be accurately obtained.