The conceptual model of mission space is the description of military operation in the real world and other related factors independent of implementation. It is the first abstraction of military activities. The modeling of the conceptual model of mission space is a vital step of the military system development. The main research includes analyzing the current research status and problems, discussing the characters of mission space, proposing and building the two-phase development methodology of conceptual model of mission space based on ontology, which can effectively improve reusability, creditability and facilitate interoperation.