In view of the large uncertainty and subjectivity in evaluating the toughness of ship power system， a method of FAHP-CM for evaluating the toughness of ship power system is proposed by combining cloud model （CM） and fuzzy analytic hierarchy process （FAHP） on the basis of establishing the evaluation index system of ship power system. The method uses FAHP-CM to calculate the weights of evaluation indicators， which makes the weights more objective and accurate， simplifies the calculation process and improves the evaluation efficiency. The results of example analysis show that the proposed evaluation method can reflect the toughness of ship power system well， and can effectively solve the evaluation uncertainty and subjectivity problems， so that the evaluation results are more scientific and reasonable.