Fatigue crack damage caused by the wave load brings the structure of jacket platform in service potential failure risk when subjected to the extreme load. However, there is lack of efficient method to evaluate the influence of crack damage on the structural performance because of the huge scale difference between the meso-scale damage and the macro-scale structure. Based on the multi-scale finite element method (FEM), to improve the efficiency of structural analysis, the damaged region of the structure is modeled with fine FE mesh (shell element) to describe the fatigue crack, and the undamaged area is modeled with coarse FE mesh (beam element). Furthermore, the applicability and superiority of this multi-scale model was validated through comparing the results obtained from the beam, multi-scale and shell models. The influence of the time-varying crack damage on the residual strength of jacket platform is then revealed based on the multi-scale FE model. The results show that the proposed multi-scale method can accurately describe fatigue crack damage in the macro-scale structure, and be applied to investigate the influence of meso-scale structural damage under the extreme load condition.