The invention discloses a self-adaption method of zero compensation detection of a rotary transformer of a permanent magnet motor. The rotary transformer detects the rotate speed, the direction of rotation and the rotor position of the permanent magnet motor; three current sensors respectively detect direct current bus current Idc, motor V-phase current Iv and motor U-phase current Iu, and rotor d shaft current Id and rotor q shaft current Iq are obtained by means of CLARK conversion and PARK conversion through a micro-programming controller; the permanent magnet motor is adjusted to be in a zero torque control mode, at the moment the Id equals to flux-weakening current and the Iq equals to zero; when a magnetic field of the permanent magnet motor is zero position alignment, the Idc is approximate to zero; in case that the zero position of the magnetic field deviates, the Idc is not approximate to zero; a rotary transformer deviation angle is regulated and rotated through the micro-programming controller until the Idc is approximate to zero and a rotor of the permanent magnet motor and a d shaft coincide. The self-adaption method can detect the accurate position of a motor rotor in real time, avoids a process of zero compensation manual calibration, improves torque control accuracy of a motor and system security, and is suitable for mass manufacturing of the motor.