Abstract: This paper discusses the estimation ctf corrosion fatigue life of offshore steel structures based on fracture mechanics. The factors affecting on the fatigue damage of structures, such as the probability of sea states, stress rages, stress ratio and loading frequency of random loads were considered. Gorrosion fatigue tests in sea water environment of ASTM A537 steel specimen were provided, and the fatigue property parameters of the steel were given according to the test results.The probability distribution of sea states of Bahai Bay was also investigated, and the method to estimate the stress spectrum of structures in various sea states by means of wind wave spectrum was proposed. An estimation formula was derived to calculate the corrosion fatigue life of offshore steel structures.