The Value of warfare simulation depends on the fidelity of the factors, which is simulated, such as military operations, equipments, systems and environments etc. How to describe the characteristics and essences of complex entity, process and interaction in real world is always one of the urgent issues that need to be done in Modeling and Simulation (M&S) research and practice. Functional Description of Mission Space(FDMS)is the first abstract of real world and the functional description that is independent of simulation realization and the common start point of authoritative and coherent M&S. To provide the authoritative, correct and normative knowledge description of real world is one of the goals for FDMS. The dissertation focuses on the key technologies of FDMS modeling, with emphasis on development process model, the nature of military mission space, technology framework and validation. It also analyses how to apply existed FDMSs to simulation developments directly and efficiently and the application of FDMS modeling for a mission space.Firstly, the dissertation puts forward the FDMS development Process (FDP) model which is a universal development method for FDMS. FDP, which starts from analysis of mission space and ends at model accessing and downloading, studies the important activities in development process roundly and divides the process into five steps. Based on the FDP, it explores the risks that might appear in each step in development process and the mature management architecture in information modeling domain and it suggests that procedural management should be put in practice from personal management, criterion management and scheme management. FDP and procedural management, which provide high level guidance and operable steps for FDMS development, help to improve development efficiency and to decrease risk.Secondly, military task architecture is very important in military field, and is the matter of military M&S research. ontology, which is the favorable tool for conceptual architecture study in information modeling domain, has attracted M&S consortium's interests. The dissertation discusses the methodology of constructing ontology, then analyses the military mission space with ontology and builds entity and behavior ontology simply. The ontologyes provide the foundation for studying military task architecture. The dissertation studies U.S. Army Universal Joint Task List (UJTL) and the methodology for developing task list. Based on the status of our troop, it brings forward that our military conceptual architecture should be built according to military entity category, entity level and operation type.Thirdly, FDMS is composed of three primary components: MSM, technical framework and repository. the dissertation brings forward a method for MSM decomposability, in which mission