The utility model relates to a permanent-magnet direct-drive electric motor formed by the stacked jointing of multiple groups of disc-type electric motor units, and the motor comprises a bearing seat, a rotor shaft, a housing, and a plurality of groups of disc-type electric motor units. The bearing seat is fixed on the housing, and the rotor shaft can be rotatingly disposed on the bearing seat. The plurality of groups of disc-type electric motor units are disposed in the housing in a stacked manner, and each group of disc-type electric motor units comprise one disc-type coil and a disc-type rotor, wherein the disc-type rotor is located at a side of the disc-type coil and beset with a permanent magnet, the disc-type coil is fixed on the housing, and the disc-type rotor is connected with the rotor shaft. Each disc-type coil is provided with a plurality of rectangular spiral coils, and stator coil windings are connected in series outside the housing and are in series or parallel connection with other disc-type coils. The motor makes the most of the internal space of a rotor, improves the power density of output, reduces the radial and axial sizes, greatly reduces the weight and cost, and can meet the demands of a low-speed high torque.