Abstract： In this paper, a limit state equation was derived by using an improved model of Paris law. A more efficient numerical integration method was described and the verification showed that the result of this method was in good agreement with that of the cyclebycycle method. A flowchart for prediction of fatigue life reliability of ship details by using Monte Carlo simulation was given. Based on this procedure, a demonstration was done for predicting the fatigue life reliability of a detail on deck of a container ship. In addition, the influences of variables on prediction result were discussed. It is shown that the improved Paris model can reduce the variation of predicted fatigue life. Initial crack size affects the results a lot while the critical crack size does not. The method proposed can provide reference for fast prediction of fatigue life or obtaining reliability of other engineering structures.