Aiming at the issue that servo motor control systems require accurate motor dynamic parameters to improve controller accuracy, this study investigates the difficulty in achieving online mechanical parameter identification in the traditional speed loop PI control of PMSM, and proposes an STA online parameter identification strategy. First, the friction torque feedforward compensation is performed using Cm and Bm obtained by RLS identification. Then, amplitude extraction is conducted based on the SOGI-QSG algorithm. On the basis of offline parameter fitting using the recursive least squares method, the proposed online mechanical parameter identification strategy analyzes the frequency characteristics of the system′s speed loop. It realizes the self-tuning of PI parameters for the speed loop of the PMSM vector control system while achieving online inertia identification of the PMSM vector control system, with simulation experiments verified using Matlab Simulink. The research results show that the STA inertia identification strategy can realize online identification of the moment of inertia while adjusting the PI parameters of the PMSM speed loop, achieving a relative error of 0.352 9%. Compared with the RLS and EKF, the accuracy is improved by 4.33% and 17.3% respectively, which proves the effectiveness and practicality of this strategy.