To address the issues of chattering and imprecise phase compensation of the low-pass filter in traditional sliding mode observer-based sensorless control of permanent magnet synchronous motors, this paper proposes a higher-order sliding mode observer with an exponential-power switching reaching law. First, a piecewise composite function is employed to replace the sign function, effectively suppressing the inherent high-frequency chattering of the system； second, by integrating the exponential reaching law and the power reaching law, an exponential-power switching reaching law is designed to further enhance the dynamic performance and convergence efficiency of the system； furthermore, a saturation function is introduced to replace the gain of the original exponential term, mitigating the chattering caused by the exponential term near the sliding surface； finally, simulation experiments are conducted to validate the proposed method. The results show that, compared with three other typical control strategies, the errors in rotational speed and torque have been significantly reduced and the rotor position is tracked rapidly and accurately. The proposed algorithm effectively suppresses system chattering while preserving its fast response characteristics, achieving precise estimation of rotor position and speed.