It was of great significance for the design, manufacture, testing, purchase, operational application and maintenance of weapon systems to evaluate the operational effectiveness of air-to-ground ammunition scientiffically and accurately. An operational effectiveness evaluation model of air-to-ground ammunition was proposed by taking advantages of set pair analysis (SPA) in dealing with system uncertain factors in comprehensive evaluation combined with grey system theory. Finally, sensitive indexes in system were obtained according to the correlation analysis of each index. It indicated that the presented model could evaluate the operational effectiveness of air-to-ground ammunition accurately and effectively. The analysis results could offer theoretical base and decision support for the manufacture and operational application of air-to-ground ammunition.