With constructiodn of the large-scale offshore wind farm developing gradually from the shallow sea to the deep sea,floating wind turbines have become a hot topic of offshore wind energy development in many countries.The traditional fixed type foundation can not meet the performance requirements of offshore wind turbines.This paper designs a triple-column semi-submersible as the foundation structure of floating wind turbines,and considering the characteristics of offshore platforms and wind turbines on the land,the commercial software SESAM for ocean engineering is used to do a numerical analysis on intact stability and damaged stability of the semi-submersible platform.The paper is mainly concerned with when the platform is inclined with a large angle and when the cabin is damaged to incline,if the floating wind turbine will overturn.Simulation results show that when one cabin or two cabins damage,the floating wind turbine will not overturn.The wind turbine can guarantee normal power generation.