The invention provides a reconstruction method and system for unmanned-aerial-vehicle formation communication topology based on a minimum arborescence. The reconstruction method includes the steps that broadcast communication channels are monitored, and whether communication failure of an unmanned aerial vehicle in a formation appears or not is judged; when communication failure of the unmanned aerial vehicle appears, a formation communication diagram is modified according to the model of the communication failure; a minimum arborescence of the modified formation communication diagram is calculated, and according to the calculated result, the unmanned-aerial-vehicle formation communication topology is reconstructed. When the communication failure of the unmanned aerial vehicle appears, the formation communication diagram is modified according to the model of the communication failure, the minimum arborescence of the modified formation communication diagram is calculated to reconstruct the unmanned-aerial-vehicle formation communication topology, and it is achieved that after the communication failure is detected, the communication topology is rapidly reconstructed so that UAV collision accidents are avoided, and a formation pattern is recovered.