In order to solve the technical difficulties in the online simulation flight communication module, the key technologies in the online simulation flight communication system are studied. Based on the UDP data transmission protocol, the algorithm is processed by time, and the shared memory and semaphore are combined to compare and analyze the multi-aircraft synchronization algorithm, and the optimal algorithm is designed to eliminate the influence of network delay and data loss. The effectiveness of the interpolation algorithm is verified by cubic spline interpolation. The verification results show that the design method can greatly improve the reliability of data transmission during online flight simulation.