In order to improve the control performance of position sensorless technology of permanent magnet synchronous motor (PMSM), a sliding variable structure controller mode was used to replace the traditional PI controller, and a new approach law was presented to improve the output of the sliding mode controller model, which had weakened the chattering of the traditional sliding mode control and improved the antiinterference ability of the control system. In the analysis of position sensorless technology, a highfrequency pulse current signal injected in twophase stationary coordinate system was characterized by a high signal to noise ratio owing to the introduction of a highpass resonant filter. The simulation results showed that the application of the sliding mode variable structure controller in the high frequency pulse current injection method with highpass resonant filtering improved the accuracy of the rotor position estimation and enhanced the robustness of the control system.