Permanent magnet synchronous motor (PMSM) parameters are affected by the environment and other nonlinear factors. So it is necessary to adjust the control system according to the motor parameters to achieve better control performance. A new step-by-step parameter identification system for position sensorless PMSM is presented to solve the problems that the parameters of different motors are different and the fast manual measurement can not be realized. The resistance is calculated by volt-ampere method in stages and the inductance and magnetic chain of the motor are calculated by high-frequency voltage injection method. The parameters of the built-in PMSM can be identified automatically under the position sensorless control. Finallythe reliability of the new step-by-step parameter identification system is verified by building a simulation model with MATLAB/Simulink and the accuracy of the system is verified by experiments.