Abstract: The dynamic reliability of offshore platform within its life cycle was analyzed. Three dynamic reliability models in consideration of fracture failure, corrosion failure and both of them were proposed. The dynamic fatigue reliability to platform system was investigated. The corresponding assessment methods and the relative formulae were given. The investigated example illustrated the validation of the proposed method. A new method to prediction of fatigue stress of offshore platform was proposed by combining the spectral method with the time domain method. The new method possesses the advantages of less computation work and more simple application.