Aiming at the shortcomings of the existing motor rotor initial position angle identification method, the mathematical model of permanent magnet synchronous motor (PMSM) was studied, and the mathematical relationship between the rotor position and the inductance of the motor winding was derived. It was proposed to determine the rotor position by using the static inductance value of the threephase winding of the motor, and use the inverter to send the excitation voltage to determine the polarity of the rotor. The rotor prepositioning was not needed during the detection process, and the detection could be realized in mechanical locking or freestop state. The experimental results showed that the method had high detection accuracy and could meet the requirements of vector control of PMSM, which had certain popularization value.