In modern warfare, joint operations and counterwork of system of systems are key development trends. It is essential to invest in weapons production, resources configuration and use of weapon in modern operations. The system portfolio selection is to select the producing, deploying and installed weapon systems from the “system” perspective and it purpose is striving to find a portfolio option that can maximize the military value. Firstly, this study introduces the basic concepts of system portfolio selection and gives the core elements and the basic process of portfolio selection. Secondly, the military characteristics and the problem essence of the weapon system portfolio selection are analyzed and the technical methods are introduced to solve these problems. In addition, a case of method application is presented. Then, the application and development of the combination selection in the military are discussed. Finally, the possible challenge of portfolio selection is analyzed and discussed in military application in the future.