To better carry out the Functional Hazard Assessment (FHA) of civil aircraft, this paper builds an evaluation index system according to the influencing factors of failure grade. And improves the traditional cloud barycenter method, applies it to the risk grade identification of failure condition in FHA, to solve the problems of randomness and fuzziness. This method not only realize the transformation between qualitative and quantitative, but also fully reflect appraisers’ judgment tendency. By analyzing an example of failure condition, it is verified that this method has good applicability and effectiveness for such problems.