According to the working characteristics of SpaceWire network in hotspot communication mode, the buffer allocation algorithm was studied. The definition of uniform communication mode and hotspot communication mode were given; the calculation method of full-load probability and the average delay of nodes in the network were deduced, and the key communication nodes in the network were calculated; the buffer allocation algorithm for SpaceWire network was derived. Then, the SpaceWire communication model was established by using the Opnet network simulation platform, and the key performance indexes of the different communication modes were simulated before and after adopting the buffer optimization strategy. The study results show that, in the hotspot communication mode, the buffer allocation algorithm reduces the average delay of the network system under the same total resource. The performance of the SpaceWire network is optimized.