The　effects　of　substrate　type　and　concentration　on　cultivation　and　stability　of　aerobic　granular　sludge　are　investigated.　During　start-up　phase,　sucrose　is　used　as　the　sole　substrate,　compact　aerobic　granular　sludge　form　in　10　days　under　influent　COD　concentration　of　600-900　mg/L,　the　mean　diameter　of　the　granule　is　1.15±0.14　mm,　SVI　is　90　mL/g.　However,　when　the　influent　COD　concentration　is　increased　from　900　to　1200　mg/L,　outgrowth　of　filamentous　bacteria　in　aerobic　granular　sludge　occur,　when　SVI　is　increased　to　175　mL/g　and　large　amounts　of　aerobic　granular　sludge　are　washed　out　of　the　reactor.　In　order　to　control　the　filamentous　growth　in　aerobic　granular　sludge,　sucrose+peptone　(1:1)　are　used　as　the　substrate　under　influent　COD　concentration　of　600　mg/L,　during　34　days,　the　filamentous　bacteria　gradually　disappear,　the　filamentous　growth　aerobic　granular　sludge　transits　to　stable　smooth　aerobic　granular　sludge　again.　When　the　influent　COD　concentration　is　increased　from　600　mg/L　to　1200　mg/L,　non-filamentous　bacteria　prevail　and　aerobic　granular　sludge　are　stable.　This　study　shows　that　substrate　diversity　and　increased　substrate　N/COD　ratio　leads　to　the　control　of　filamentous　growth　in　aerobic　granular　sludge.