Landing gear is one of the important devices in a flying vehicle. A type of tiltrotor UAV was taken as the research object, and the landing gear layout was set based on various factors such as weight, stability, crash resistance and UAV characteristics. By combining the design parameters such as focus, center of gravity, load ratio and brake antitip, the landing gear installation position was quickly determined. In order to avoid the aerodynamic loss of the tiltrotor UAV under highspeed cruise, a set of singleside tetrahedral loadbearing retractable landing gear structure was designed to meet the requirements of retracting space by increasing the angle between the main rotating axis of the main landing gear and the horizontal line of the spreading direction. The main landing gear with this structure is stowed in the chord direction and the supporting parts such as buffer struts move along the spreading direction to the inside of the fuselage. Through the reasonable design of the wheel rotating mechanism, it is possible to avoid the large angle between the wheels and the aircraft fuselage without adding power source.