The invention relates to the technical field of complete equipment of a coal mine underground working face, in particular to a moment-limiting permanent magnet synchronous frequency conversion directdrive crusher which is arranged in a gate way and is used for crushing raw coal and gangue. The crusher is composed of a permanent magnet synchronous frequency conversion motor, a self-recovery torque-limiting coupling assembly, a hammer shaft assembly, a crushing cavity assembly and the like. The self-recovery torque-limiting coupling assembly is connected with the permanent magnet synchronous frequency conversion motor and the hammer shaft assembly, and the hammer shaft assembly is installed in the crushing cavity assembly. The permanent magnet synchronous frequency conversion motor transmits the rotating speed and the torque to the hammer shaft assembly through the self-recovery torque-limiting coupling assembly, the large inertia hammer shaft assembly is dragged to rotate, and raw coaland gangue are crushed. The permanent magnet synchronous frequency conversion motor can provide low-speed high-torque output, so that the soft start of the crusher is realized; when the impact load exceeds the set allowable load, the self-recovery torque limiting coupling assembly starts to slip and unload, and when the load is lower than the allowable load, the slip is stopped, and the torque limiting function can be automatically recovered.