Abstract: In terms of sensorless control for permanent magnet synchronous motor (PMSM), phase locked loop (PLL) can be used to acquire the speed, thus suppressing the noise of differentiation after the back electromotive forces or fluxes are estimated. In order to improve the transient performance of the speed estimation, a novel extended-state-observer-based (ESO-based) high-order PLL considering the transient states was proposed. The phase detector (PD) was the error between the angles acquired by the arctangent and PLL. The loop filter (LF) was the ESO to replace the PI controller. The voltage-controlled oscillator (VCO) was the process of angle estimation in the ESO. This method was easy to implement, and mechanical parameters were not used. The research results demonstrate that the proposed ESO-PLL could be operated stably, and the transient performance is superior to the conventional PLL.