A motor mechanism of DC inverter-fed compressor is disclosed, wherein a motor rotor includes a first rotor layer, a second rotor layer and a third rotor layer, made up respectively of a plurality of rotor units stacked together. The rotor units have a shaft hole in the middle and have at least one magnet slot that install a permanent magnet at every quarter surface area of the rotor units. The rotor units of the first rotor layer have a plurality of first holes at one of the quarter areas thereon, and the rotor units of the third rotor layer have a plurality of third holes, which are set up at an area opposing the first holes. The present invention can reduce the height of the compressor, the costs of parts and assembly, and increase the total efficiency of the motor and the compressor.