To address the challenges of finite-time convergence and chattering induced by high gain in traditional sliding mode control， a novel composite control strategy is developed to enhance the performance of permanent magnet synchronous motors. This strategy integrates a nonsingular fast terminal sliding mode control （NFTSMC） algorithm with a generalized proportional-integral observer （GPIO）. A sliding surface incorporating nonlinear terms is constructed to ensure finite-time convergence， while the GPIO facilitates real-time observation and feedforward compensation of time-varying disturbances within the speed loop. The switching gain is regulated to mitigate chattering effectively. Simulation and experimental results demonstrate that， under a 100 r/min step tracking input， the settling time is reduced to 1.08 s-representing a 32% improvement over conventional PI control-steady-state error decreases to 2.56 r/min， and overshoot is lowered by 7.51%. Upon application of a sudden 2.5 N·m load， precise disturbance estimation via the GPIO not only suppresses chattering but also constrains maximum speed fluctuations during loading and unloading to 105.81 r/min and 93.72 r/min， respectively， which is 7.51% lower than PI control， with a faster recovery to the rated speed. Fast Fourier Transform （FFT） analysis reveals that harmonic components of speed （1_st， 2_nd， 6_th， and 12_th） are attenuated by 65%， 29%， 60%， and 47%， respectively， following the incorporation of the observer. In sinusoidal position loop tracking experiments， the maximum commutation error is reduced by 47% and the root-mean-square tracking error decreases from 0.25 to 0.13 with the GPIO observer， improving position tracking accuracy by 48%. These findings substantiate that the proposed control method achieves superior chattering suppression， accelerated dynamic response， and enhanced disturbance rejection capability.