The real-time distributed computing environment and reusable software architecture are important factors that affect the fidelity of flight simulation. We accomplished a flight simulator based on DDS (Data Distribution Service for Real-time Systems) middleware and structural software architecture and proved its high fidelity as a flight training device. According to the analysis of flight simulator’s functional blocks, we developed the real-time distributed computing environment which utilized DDS middleware through Ethernet and decreased the communication latency among functional blocks. Furthermore, we proposed the structural software architecture on the basis of layered and component-based design pattern to facilitate the higher simulation components’ reuse and replacement. The real-time communication procedures among simulation components are also described in this paper. The validation method and the contrasting simulation results are presented finally to show the feasible design based on DDS to carry out flight simulation with low communication latency and high quality.