Abstract: To simplify the design of the controller and enhance the robustness of the system, a sensorless control method for permanent magnet synchronous electric spindles is proposed based on the Luenberger observer. Initially, a mathematical model of the electric spindle is established, followed by the introduction of the state equations of the Luenberger observer. Linear control techniques are employed to construct the observer model. After obtaining the back electromotive force(EMF) from the observer, the rotor position and speed are acquired by integrating a phase-locked loop(PLL). The proposed method is validated using an FL170-20-15 high-speed electric spindle. Experimental results demonstrate that this control method features a simple structure and provides accurate estimation of the spindle rotor position and speed.