The　denitrification　performance　of　simultaneous　anammox　and　denitrification　(SAD)　granular　sludge　under　different　C/N　was　studied　by　batch　test.　The　coupled　system　granular　sludge　was　cultured　in　a　UASB　reactor　with　sufficient　nitrogen,and　it　had　high　anammox　activity　and　denitrification　activity.　Using　glucose　as　carbon　source,　when　the　C/N　were　1,　2,　4,　there　was　no　significant　difference　in　the　activity　of　ANAMMOX,　and　the　denitrification　activity　increased　gradually.　The　maximum　rate　of　NO2--N　degradation　was　0.265,　0.345,　and　0.453kgN/(kgVSS•d),　respectively.　When　sodium　acetate　was　used　as　the　carbon　source　and　the　C/N　ratios　were　1,　2,　and　4,　respectively,　neither　of　the　ANAMMOX　activity　or　the　denitrification　activity　was　affected.　Under　the　same　C/N,　the　activity　of　ANAMMOX　with　glucose　as　the　carbon　source　was　higher,　while　the　denitrification　activity　with　sodium　acetate　as　the　carbon　source　was　higher.When　C/N　was　1,　2　and　4,　the　maximum　degradation　rate　of　NH4+-N　with　glucose　as　organic　matter　was　1.15,　1.19,　1.58times　of　sodium　acetate　respectively.　The　maximum　degradation　rate　of　NO2--N　with　sodium　acetate　as　organic　matter　was　1.89,　1.48　and　1.15times　of　glucose,　respectively.　The　mathematical　simulation　results　of　the　experiment　showed　that　the　models　can　accurately　predict　the　trend　of　nitrogen　change　during　the　experiment.　There　was　no　significant　change　in　the　ANAMMOX　activity　of　the　granular　sludge　in　the　coupled　system　when　the　C/N　ratio　was　1~4.　©　2018,　Editorial　Board　of　China　Environmental　Science.　All　right　reserved.