Community of Simulation task (CoST) is a simulation architecture based on a service-oriented architecture to achieve seamless integration and interoperability of command information system. It servitize the simulation resources through combination the simulation service and completes CoST by management and coordinated simulation resources. Firstly, this article introduced in the CoST involves simulation service, simulation resources, CoST, CoST members as well as simulation service system concept and CoST's principle. Secondly, the article describes CoST's architecture and key technologies of simulation task to solve problem. Finally, combining tasks of joint training simulation control system with hierarchical structure describes CoST�s application in detail.