The　solids　segregation　of　both　solids　reactant　and　product　were　studied　in　a　rectangular　gas-liquid-solid　three-phase　fluidized　bed　reactor　in　presence　of　a　special　internal,　which　was　constructed　of　multilayer　shutter-like　baffle.　The　influence　of　the　numbers　of　shutter　layers,　gas　and　slurry　volumetric　flowrate　on　solids　segregation　was　experimentally　investigated.　A　segregation　index　was　proposed　for　describing　the　solids　segregation　behaviors　in　the　bed.　The　results　showed　that　the　presence　of　the　multiplayer　shutter-like　baffle　promotes　particles　segregation　significantly,　and　that　the　gas　and　slurry　flowrate　has　little　effect　on　the　solids　segregation.　The　mechanism　behind　effect　of　the　internal　on　solids　segregation　was　also　discussed.