Abstract: To improve dynamic quality of permanent magnet synchronous motor（PMSM） speed servo system,a novel reaching law was proposed,different from the conventional reaching law,switching function was not included in the novel reaching law,and the terminal attractor and the system state were used to suppress the chattering and improve the reaching speed.The novel reaching law was applied to the PMSM speed servo system;a novel sliding mode speed controller was designed to replace the traditional PI regulator.Simulation and experimental results show that the novel speed controller can improve steady,dynamic performances and robustness characteristics of speed servo system obviously.