Abstract: A new floating foundation composed of three pontoons and three columns was designed for a 10 MW offshore turbine in a water depth of 50 meters, and a finite element analysis model with stiffeners structure was established. The design wave parameters of new floating foundation were determined by random design wave method, and the strength of the overall structure under wave load condition was analyzed. The influence of the size and the spacing of the pontoons on the strength of new floating foundation of pontoon was studied, and the influence of longitudinal and transverse stiffeners size combination on the overall strength of new floating foundation was obtained. It is found that the high-stress area of the new floating structure is located at the connection of the three pontoons, and the stress level of the pontoon is affected by both the size and the spacing of the stiffeners.A appropriate size spacing combination can significantly reduce the steel consumption with comparable stress levels. This paper can provide a reference for the design of semi-submersible offshore wind turbine structures.