Solving　the　coupled　Raman　amplification　is　the　main　limitation　to　the　efficiency　of　the　existing　optimization　method　for　Raman　fiber　amplifier　design.　The　least　squares　support　vector　regression　model　is　applied　to　address　this　issue.　Instead　of　directly　calculating　the　Raman　coupled　equation,　a　multi-input　multi-output　model　for　Raman　fiber　amplifier　is　established.　A　C-band　Raman　fiber　amplifier　with　a　gain　ripple　level　of　±　0.5　dB　is　designed　using　only　two　pumps.　Additionally,　the　on-off　gain　can　be　quickly　and　directly　adjusted　by　the　proposed　model.　Compared　with　the　shooting　algorithm　and　average　power　analysis　technique,　the　results　indicate　that　the　proposed　regression　model　greatly　improves　the　solving　efficiency.　©　2015,　Chinese　Laser　Press.　All　right　reserved.