Abstract: Weapon system combat capability assessment, which has important military significance, is a multiattribute decision making problem with a complex data structure. Aiming at the problems such as the inconsistent form of information, the difficulty of aggregating criteria data and the incomparable analysis of different criteria, this paper proposes a multiattribute utility assessment method with subject and object fitting. The utility function is constructed based on the constants of psychology activities, and a criteria utility aggregation model based on the production function is established. First of all, based on the method of group decisionmaking, this paper proposes to combine the distance optimization model and the multiexpert evaluation weight to obtain effective criteria weights based on group consensus. Secondly, considering the problems that the form of assessment information is not uniform and the data of different attribute criteria cannot be compared and analyzed, based on the characteristics of psychological activities, three types of utility functions are constructed to convert all kinds of weapon information into utility. Finally, aiming at the difficulty of aggregation of criteria data, based on the characteristics of the production function, a utility aggregation model that conforms to the law of capability growth is established. The case study shows that this method can effectively assess the combat capability of the main battle tank, and the criteria data are objective and comparable. The ways of increasing the capability of main battle tank in our country is analyzed, which provides references for equipment improvement and new equipment development.