In order to achieve the deterministic transmission of the massive real-time data streams in a short time on the SpaceFibre onboard data network, the time-slot allocation algorithm of QoS (quality of service) for SpaceFibre was proposed. Formally the QoS of SpaceFibre network was described and the definitions of scheduling matrix were given; the queuing model of QoS was created and the impact of time-slot allocation on delay performance was quantitatively analyzed; From the perspective of network compatibility and robustness of algorithm, an improved binary sequence scheduling sub-algorithm was derived; the improved hybrid partheno-genetic scheduling sub-algorithm with the highly evolved initial population and more genetic operators was given; the SpaceFibre communication model was established by using the Opnet network simulation platform to compare with the delay performance under different algorithms. Simulation results show that the time-slot allocation algorithm has lower average latency compared with other algorithms. The performance of the network is optimized. The research results can provide a reference for building a low-latency SpaceFibre network.