The main rotor system is the design center of the helicopter and other rotorcraft. The rotor hub has been a very complex mechanical system in the past, especially for fully articulated rotor systems. In order to reduce this complexity, the main rotor hub is continuously developed to the bearingless hub. The bearingless rotor is the latest development stage of hingeless rotors. For this reason, the research on the bearingless main rotor hub has been started by the major helicopter companies. At present, the bearingless rotor has formed a series of products overseas, and successfully applied to a variety of helicopters. In this paper, the basic configuration of the main rotor hub is briefly introduced, and then the technical characteristics of typical bearingless rotor systems are reviewed in order to provide theoretical support for the research and development of bearingless main rotors in China.