Conceptual modeling is crucial and essential activity during the simulation research and development process. A simulation conceptual model is a simulation developer's way of translating modeling requirements into a detailed design framework. It is the foundation to provide simulation developers establishing the consistent and authoritative model and simulation - representation, from which the software, hardware, networks, and systems/equipment that will make up the simulation can be built. The complex simulation is developed by many development agents and developers who concern about different things. To describe simulation conceptual model clearly, according to the characteristics of the simulation model, a layered simulation conceptual modeling approach is offered and the conceptual model is defined and described in terms of strategy, system and object aspects. Then a modeling process model for the simulation conceptual model is given and corresponding representations are provided to the layers of strategy, system and object. The layered simulation conceptual mode provides foundation for subsequent simulation design and development and the criteria for the simulation WA.
