The invention discloses a bandwidth reservation-based very small aperture terminal (VSAT) satellite communication system bandwidth distribution method, and relates to the technical field of satellite communication. In the method, different applications are endowed with different priorities based on the conventional bandwidth reservation-based dynamic bandwidth distribution method, and the high-priority application can occupy the bandwidth section occupied by the low-priority application, vice is not; and in actual distribution, when the bandwidth section corresponding to the application has no enough idle bandwidth, and the bandwidth sections with low priorities are searched in turn from high priorities to low priorities. The method keeps the advantages of the conventional bandwidth reservation-based dynamic bandwidth distribution method such as simple implementation, few channel fragments and high distribution speed, coordinates different QoS (quality of service) demands and application scenes, realizes effective management of channel resources, improves the utilization rate of satellite channel resources in a network environment of multiple service types, meanwhile, simplifies star-earth interaction and reduces the time delay caused by bandwidth distribution.