In　a　vertical　gas-liquid-solid　fluidized　bed　of　4.2　cm　in　diameter　and　130　cm　in　height,　the　axial　solid　concentration　distribution　is　investigated　for　two　kinds　of　particles　with　different　properties.　Two　distinguishing　systems　can　be　formed　upon　the　wettable　property　of　particle　materials.　One　is　called　as　a　no-attached　system,　in　which　the　solid　holdup　decreases　with　the　increase　of　bed　height.　Another　is　named　as　an　attached　system,　in　which　solid　holdup　increases　with　the　increase　of　bed　height.　The　sedimentation-dispersion　model　can　be　employed　better　to　describe　both　above　systems　by　modifying　only　one　model　parameter,　i.e.　the　particle　terminal　settling　velocity,　which　considers　the　effect　of　an　additional　drag　force　resulting　from　attached　up-flowing　bobbles　and　subtracts　a　certain　value　obtained　by　a　function　formula　relating　to　the　gas　velocity.　It　is　found　that　the　axial　concentration　profiles　of　solid　particles　predicted　by　the　modified　sedimentation-dispersion　model　are　in　good　agreement　with　experimental　results　for　both　no-attached　and　attached　systems.