The position sensorless control of permanent magnet synchronous motor reduces the cost and maintenance difficulty of the system and avoids the problems arising from sensor failure, but there are some shortcomings concerning dynamic performance and robustness, etc. In view of the jitter problem inherent in the traditional sliding-mode observer, this paper will use the super-twisting algorithm to improve it, and achieve the suppression of jitter vibration and reduce the error caused by high frequency jitter vibration when obtaining the position information of the rotor by including high-frequency switching into the integral term for observing the reversed electromotive force to make the system position and speed estimation more accurate. By including the high-frequency switching in the integral term, the jitter suppression is achieved, the error caused by the high-frequency jitter is reduced when obtaining the rotor position information, and the inverse electromotive force is observed, so as to make the system position and speed estimation more accurate. And the online parameter identification method is used to improve the problems such as system performance degradation caused by parameter errors. Finally, a simulation comparison analysis is carried out on MATLAB/Simulink, and it is concluded that the use of the super-twisting sliding mode algorithm has a great degree of improvement in the elimination of jitter vibration.