Abstract: Calculation of nuclear equipment design life should consider the influence in service environment. Because the fatigue curves in current regulation do not take into account the impact of in-service environment, the fatigue cumulative usage factor can be modified by the environmental fatigue correction factor. During the correcting, three kinds method have been proposed. Based on above different methods, the fatigue cumulative usage factor has been corrected separately. Meanwhile, the results have been contrasted with each other and the results under air environment. The results showed that the fatigue cumulative usage factor bigger than it under air environment. Furthermore, parameter transformation of environmental fatigue correction factor with results of thermal-structure field calculation more conservative than with the results of transient combination.