To improve disturbance rejection ability of permanent magnet synchronous motor (PMSM) system, a novel sliding-mode reaching law is proposed in this paper. Then, based on this reaching law, a sliding-mode load torque observer is presented, which is used as feedforward value to compensate the output of speed PI regulator. Simulation results show that system robustness can be enhanced greatly and the sliding-mode control (SMC) inherent chattering can be weaken effectively.