Aimed at the problems that UAV is high mobility at nodes, flying ad hoc networks are drastic changes in network topology and frequent link disconnection. Reactivegreedyreactive (RGR) routing protocol is proposed with a good network performance in high dynamic environment. In view of high network overhead and network congestion, an improved RGR routing protocol (LBHGSRGR) based on load balancing and high greedy geographical forwarding success probability is proposed. Based on the RGR protocol, three key improvement measures are proposed, which are scoped flooding mechanism based on node load status and geographic location information, path selection strategy with high packet success probability in GGF mode, and packet forwarding strategy based on node load prediction and motion characteristics. The simulation results show that compared with AODV, RGR and their improved protocols, this protocol improves packet delivery rate, reduces network control overhead and average endtoend delay, improves the ability of network to cope with highly dynamic topology changes, and effectively improves network performance.