The invention relates to a stability evaluation method and device for a PMU (Power Management Unit) or WAMS (Wide Area Measurement System) business performance index. Various types of business under wide area stability control is aimed at to carry out stability evaluation on a performance index by taking PMU or WAMS business as an example, a hierarchical structure mode is reasonably selected to construct a stability evaluation index system, a fuzzy analytical hierarchy process and an entropy weight method are comprehensively utilized and combined so as to determine evaluation weight to obtainthe comprehensive index of PUM or WAMS business stability, and the development tendency of the business stability is judged. The evaluation method is high in accuracy and is favorable for performing an instructional function for the optimization and the development of a whole wide area stability system.