Six-phase permanent magnet synchronous generator (PMSG) has broad application prospects due to its low harmonic content, mature decoupling methods, and strong stability. To improve the dynamic performance of the six-phase PMSG when the load torque suddenly changes, and to enhance the system’s anti-interference ability, a feedforward compensation strategy using the load torque observation value is proposed. Firstly, the load torque is observed by the sliding-mode observer, the sliding surface of the observer is designed as the difference between the actual speed and the observed speed, and the chattering signal can be filtered out during the observation process without causing phase and amplitude changes. Secondly, the load torque observation value is proportionally feed forward to the given value of the current loop, making up for the problem of insufficient amplitude of the discontinuity term of the sliding mode controller. Thirdly, for the problem that the feedforward proportion constant is too large, resulting in the speed not being able to quickly stabilized at the given value, the feedforward proportion coefficient is set to a variable value, which effectively suppresses the speed fluctuation. Finally, based on Matlab/Simulink, the simulation model of multi-phase-modular multilevel converter (MP-MMC) drive six-phase PMSG load torque observation feedforward sliding-mode control is established to validate the proposed stratage. The simulation results show that the sliding-mode observer can accurately observe the load torque, and the feedforward compensation strategy effectively suppresses the speed fluctuation caused by the sudden load change. 