A servo motor with large rotor inertia includes a casing, a stator, a rotor and an inertial disk. The casing includes a hollow chamber and axial stages at front side and rear side thereof. The stator is arranged in the chamber and includes a ring and a plurality of coils around the ring. A through hole is defined at the center of the ring. A rotation shaft of the rotor is fixed to the stage and a magnet body is capped to the rotation shaft, where the magnet body is arranged in the through hole. The inertial disk is fixed to the rotation shaft of the rotor. The rotational inertia of the rotor is increased by rotating the inertial disk when the rotor is rotated by magnetize the stator. Therefore, the inertial disks of various sizes can be fixed to the rotor for matching different load inertia.
展开▼