With the development of technology, small satellites have become a kind of powerful spacecraft. In order to further expand the application field of small satellites and improve its mission efficiency, the high agile maneuvering ability has become an important direction in the development of small satellites. The control moment gyroscopes (CMG) will be an important actuator for the agile maneuvering of small satellites because of its high torque energy ratio and low weight torque ratio. The angular momentum of the control moment gyroscopes comes from its rotor component. A new rotor component of miniature CMG, with an angular momentum of 0.5Nms, which can be applied to small satellites, is introduced in this paper. Angular contact ball bearings are installed face to face as the rotating support of the rotating mass body. In the case of no oil supply system, the bearing base oil has been added and the oil content of the bearing cage is controlled to achieve a 2-year space environment lubrication life of the bearing. The high-speed motor rotor is built into the rotating mass body to form an integrated motor rotor component. Finally, the optimized rotor component has the advantages of compact structure, small volume, light weight and high torque energy ratio.