Inoculate　mature　aerobic　granular　sludge　at　room　temperature　in　an　anaerobic/aerobic　alternate　continuous　flow　system　composed　of　independent　anaerobic　tanks　and　aerobic　tanks,　control　the　effect　of　mixed　liquid　reflux　ratio　and　organic　load　on　the　removal　of　COD,　TN　and　TP　by　anaerobic　and　aerobic　alternating　continuous　flow　process.　The　results　showed　that　the　two-stage　continuous　flow　process　can　achieve　better　nitrogen　and　phosphorus　removal　performance　by　adjusting　a　lower　reflux　ratio　when　the　influent　organic　load　was　low.　The　average　concentration　of　COD,　TN　and　TP　in　the　effluent　was　18.78,　5.79　and　0.49mg/L.　The　average　removal　rate　was　93.76%,　84.3%　and　83.12%　respectively;　when　the　organic　load　was　higher,　the　long-term　two-stage　continuous　flow　system　lacked　the　environmental　stress　of　feast　and　famine,　resulting　in　filamentous　bacteria　growth,　deterioration　of　system　performance.　The　model　was　used　to　characterize　the　granular　sludge　and　system　effluent　at　different　stages.　The　results　showed　that　the　organic　load　has　a　greater　impact　on　the　production　of　intermediate　products　related　to　the　utilization　of　foreign　substrates.　The　influent　with　lower　organic　load　could　effectively　reduce　the　generation　of　intermediate　products　in　the　effluent.　In　summary,　in　the　actual　secondary　urban　sewage　treatment　plant,　the　anaerobic/aerobic　alternating　continuous　flow　process　was　not　suitable　for　long-term　operation　under　the　organic　concentration　(500mg/L)　of　the　emission　limit.　©　2021,　Editorial　Board　of　China　Environmental　Science.　All　right　reserved.