Aiming　at　the　problem　of　low　data　rate　in　autonomous　underwater　vehicle　(AUV)-based　underwater　acoustic　communication　system,　a　hybrid　magnetic　induction　(MI)　and　reconfigurable　intelligent　surface　(RIS)-assisted　communication　strategy　is　proposed　to　maximize　system　channel　capacity.　Specifically,　an　AUV　first　collects　data　from　all　the　seafloor　nodes　by　adopting　the　MI　communication　technology.　Then,　the　AUV　forwards　the　data　to　another　AUV　carried　with　a　RIS　by　using　the　underwater　acoustic　communication　method.　With　the　help　of　the　RIS,　a　strong　reflective　path　between　the　first　AUV　and　a　surface　base　station　(BS)　on　the　sea　is　formed.　The　surface　BS　could　receive　the　data　at　a　relatively　high　data　rate.　In　order　to　maximize　the　system　channel　capacity,　the　acoustic　incidence　angle,　the　distance　between　the　first　AUV　and　the　RIS,　the　distance　between　the　RIS　and　the　surface　BS,　acoustic　signal　frequency,　and　transmitting　power　are　jointly　optimized.　The　formulated　optimization　problem　is　solved　by　employing　a　butterfly　optimization　algorithm　(BOA)　and　an　improved　butterfly　optimization　algorithm　(IBOA),　respectively.　Simulation　results　show　that　the　IBOA　can　increase　the　system　channel　capacity　more　effectively　than　the　basic　BOA.　©　2024　IEEE.