The control accuracy of traditional sliding mode observer (SMO) based permanent magnet synchronous motor (PMSM) was low, which was caused by the inherent buffeting characteristics, the weakening of observed back electromotive force (EMF) amplitude and the shifting of the observed rotor phase. In order to solve this problem, an estimating method for PMSM speed and rotor position based on the secondorder hybrid terminal SMO was proposed. The method adopted a secondorder sliding mode switching surface constructed by a linear sliding mode and a hybrid terminal sliding mode. A reasonable sliding mode control law was designed to effectively suppress the inherent buffeting characteristics of the traditional sliding mode. Besides, it could avoid the weakening of the observed back EMF amplitude and the shifting of the observed rotor phase, which were brought by the use of lowpass filter, so that the accuracy of estimated rotor position and speed could be improved effectively. On this basis, the robustness of the SMO was further analyzed with perturbation of motor stator resistance and inductance. Experimental results verified the effectiveness and practicability of the hybrid terminal SMO.