The design of the multi-UAVS and formation simulation system is proposed for realizing the flight simulation of multi-UAVS formation. Based on the research of system requirements, the overall system and structure frame are designed. Following the technique frame of HLA(high level architecture), Using visual modeling tool-Multigen Creator, visual simulation software-Multigen Vega Prime and HLA simulation support plat-RTI, A multi-UAVS formation flying simulation system based on HLA/RTI is designed. RTI is communications support layer, Establish a real-time communication of multi-machine flight simulation system, Receive orders form managers and store the flight results in real time, simulation people can be analyzed the results to improve the flight effect.