Without a unified top-level design of the system of systems （SoS） construction， the elements of the SoS will fight against each other， and hence the SoS will inevitably face problems such as inconsistent indicators， mismatched functions， and irregular integration. In order to solve these problems， it is necessary to adopt SoS engineering method and carry out forward design. The types， characteristics and the construction requirements of the SoS in the military domain are analyzed. Aiming at realizing the combat ability， the model-based SoS engineering construction method is given， according to the four stages of “SoS design， SoS construction， SoS application， SoS evaluation”. Employing digital means to support SoS research and application is introduced. By using digitization， SoS engineering， processes and tools are integrated to create a new SoS engineering construction mode.