To improve the real time performance of simulation system based on HLA, and make it be taken on hardware-in-loop simulation system, a novel method based on HLA bridge was proposed. By using this strategy to interconnect federations, the federations execute in the form of parallel computing. After describing the structure of HLA bridge, the design and implementation of a HLA simulating system based on HLA bridge and parallel RTI are introduced in detail. Then the publish-subscribe function, update-reflect function and equal time step advance function of HLA bridge are realized. At last, simulation results show that the real-time performance of simulating system based on HLA bridge and parallel RTI is better than that of original system. This is an effective method in real time performance improvement.