In the traditional sliding mode observer based sensorless field oriented control scheme for permanent magnet synchronous motor (PMSM), the fundamental wave of the observed back electromotive force ( back-EMF) has high frequency harmonics and chattering problem, and the observed rotor position is not accurate enough. Focused on these problems, a PLL adaptive sliding mode observer based sensorless control method for PMSM is proposed. Firstly, under the premise of Lyapunov stability, adaptive rule of back EMF is established and deduced. It makes the error of the observed back-EMF decline rapidly by constructing the adaptive sliding mode observer. Meanwhile, the rotor position is obtained by introducing the rotated influence immune phase-locked loop, which eliminates the influence of rotation speed change and further improves the observation accuracy. Finally, the experimental results based on a 2. 9 kW PMSM show that the proposed method can effectively suppress the chattering of the sliding mode, reduce the high frequency harmonics of the back-EMF, and improve the observation accuracy of the rotor position.