A jacket platform for offshore wind power booster station is selected, and the fatigue damage is investigated by Miner linear cumulative fatigue damage and rain flow counting method. The Finite Element Model (FEM) is established on the basis of the offshore platform blueprint. The stress-time history of different structural nodes under all short-term sea states in the whole year is calculated based on annual wave dispersion map. The hot spot stress of the selected nodes is calculated by ANSYS. On this basis, the fatigue life of the platform is assessed according to the S-N curve recommended by API. The fatigue life of the platform is about 66 years, and meet the design requirement.