Abstract: Aiming at the shortcoming of the membership function being used to evaluate multi-levels in the traditional AHP-fuzzy comprehensive evaluation method, this paper presents an assessment method based on the curve characteristics of equipment performance degradation. Depending on the actual descent of the device performance when disturbed, the level of assessment and the transition range of the membership function among different levels are determined, finally obtaining the membership function model that is applicable to the assessment of specific equipment. The method can accurately calculate the specific classes and membership values of different equipment or subsystem and overcome the problem of subjectivity that may cause errors in traditional membership functions. To analyze the weight of the equipment, expert scoring was introduced meanwhile, the credibility of expert weight is analyzed by bringing in the confidence factor. A complex communication system evaluation model of the ship is established eventually, whose results of assessment are improved effectively.