The tilt rotor aircraft has a rotatable engine on the tip of every wing. It makes the aircraft to take off and land vertically and fly horizontally. The rotation structure is the unique structure that distinguishes it from ordinary aircraft. No public information has been found on the rotation structure of large tilt-rotor aircraft.By comparative research, a kind of structure which can make rotor rotation and some related structures such as engine arrangement were designed. Three-planet gear structure was used to satisfy the load distribution. The design can make the structure practical, stable and reliable. It can be modular production. Using quantitative analysis method, a simple mechanical analysis was carried out on the stress of the relevant structures in several main flight states of the aircraft, and preliminary theoretical calculations were conducted on shaft strength, shaft diameter, rotating motor, and the strength requirements of wing ends. Research has found that the position of the center of gravity of the tilting and rotating parts and the body parts relative to the wing axis has a significant impact on the torque of the wing. The research provides some basic design and theoretical numerical calculations for the development of such aircraft. Research has found that the position of the center of gravity of the body parts relative to the wing axis has a significant impact on the torque of the wing. The research provides the basic design and theoretical numerical calculations for the development of such aircraft.