A new concept of Agile Model and Simulation (AgMS) is proposed. The characteristics of agile simulation are flexible, extensible, adaptable, composable and strong interaction. In this paper, the concept, framework and key issues of agile simulation are researched with the demand for the meta-synthetic engineering of complex systems. Through the introduce of agile simulation into the meta-synthetic system, the experts system and the simulation system are syncretized with each other and become a parallel system, which can be co-evolution. The research of agile simulation will provide new ideas for complex system study, open up new paradigm of simulation application, and promote the widely application of metasynthetic system.