Introduction　is　given　to　the　content　of　activated　sludge　model　No.3　(ASM3).　The　simulation　program　which　based　on　the　integration　of　ASM3　and　Anaerobic　Digestion　Model　was　used　to　simulate　A(2)/O　with　AquaMats　Process.　The　predicted　results　of　effluent　COD,　NH3-N　and　NO3-N　accorded　with　the　actuality.　The　removal　efficiency　of　TP　was　quite　low　when　sludge　return　rate　was　100%.　Based　on　this　condition,　the　improved　scheme　which　adjusts　sludge　reflux　ratio　to　60%　was　put　forward　and　simulated.　Process　was　optimized　depending　on　the　simulation　results　and　the　removal　efficiencies　of　COD,　NH3-N　and　TP　reached　to　83.1%,　98.75　and　24.01%.　It　is　verified　that　ASM3　can　be　used　as　the　platform　of　activated　sludge　process　design.