Aiming　at　the　threat　of　eavesdropping　in　unmanned　aerial　vehicle　(UAV)-assisted　communication　networks,　multiuser　secure　communication　with　multi-relay　nodes　and　multi-eavesdropping　threats　is　investigated　in　this　paper.　By　deploying　a　dual-antenna　UAV　relay　node,　a　hybrid　decode-and-forward　(DF)　and　amplify-and-forward　(AF)　protocol　is　considered　to　transmit　data.　In　addition,　cooperative　jamming　techniques　are　used　in　order　to　improve　the　performance　of　the　secure　confidential　communication.　The　secure　communication　problem　is　formulated　as　an　optimization　problem.　The　goal　is　to　maximize　the　minimum　secrecy　transmission　rate　subject　to　UAV　transmitting　power,　user　transmitting　power,　and　channel　bandwidth.　By　introducing　a　grey　wolf　optimizer　(GWO),　the　suboptimal　solution　is　obtained.　Simulation　results　show　that　the　GWO　has　higher　secrecy　transmission　rate　than　the　firefly　algorithm　and　the　average　bandwidth　and　fixed　transmitting　power　method.　©　2023　IEEE.