Nowadays,there exist different data sources in combat effectiveness evaluation,such as simulation data,expert evaluation data,and measured data.The various data may contain different evaluation criteria,and even sometimes contain contradictory information.How to effectively fuse the different data sources to build up a robust effectiveness evaluation method has become one of the key problems in effectiveness evaluation.In this paper,different evaluation methods are used for different information sources and decision fusion is made based on DS reasoning.Considering that contradictory decisions may exist among different data sources,a revised DS evidence theoretical formula is established by revision of both the combination rule and evidence source.Thus a modified DS evidence reasoning is established.