A method of obtaining a parameter of a synchronous motor is disclosed and includes: setting an operating current of the motor; providing a positive fixed voltage to the motor and monitoring a feedback current from the motor; recording a triggering time for the feedback current to reach the operating current; providing a negative fixed voltage to the motor for the triggering time; obtaining a square-wave voltage with a fixed frequency based on the positive fixed voltage and the negative fixed voltage being provided; providing the square-wave voltage with the fixed frequency to one axis of the motor; transforming three-phase current from the motor into an axial current; computing an inductance value of this axis based on the fixed frequency, the square-wave voltage and the axial current; and, creating an inductance-current parameter table based on a plurality of the inductance values and the axial currents correspondingly.