The capability model of combat system of systems and measurement method of armament contribution are studied to improve the building and operating of it. Firstly, composition of combat system of systems and capability factors are analyzed, from which the concept and representation of armament contribution are provided. Secondly, the capability model of combat system of systems is established based on logistic regression model. Thirdly, a measurement method of armament contribution to combat system of systems is gained. Finally, the usability and effectiveness are demonstrated through an application example. The achievement could provide reference to assess the armament contribution to combat system of systems.