In order to solve the complex simulation mission of netting many fight simulators with command simulator, the paper studied and designed a new group training system of simulator based on high level architecture (HLA). Based on certain type airplane simulator and flight command simulator, the system structure of group training system by netting many current fight simulators with a current command simulator is presented. By adopting HLA/RTI as system structure and support platform, and upgrading the command and training simulator, the group training system can carry out each flight subject in four kinds of weather conditions. The simulation result shows that the system can reduce the wastage of actual equipment and ensure the flight security, has important military training value.