To　optimize　the　function　effect　of　the　micropore　aeration　oxidation　ditch　with　selector　and　anaerobic　zone　(pre-zone),　the　influence　of　returned　sludge　ratio,　its　distribution　proportion　and　THR　in　the　pre-zone　on　nitrogen　and　phosphorus　removal　were　studied　by　conducting　the　three-level　orthogonal　experiments.　Through　the　analysis　of　range　and　variance　of　TN　and　TP　removal　efficiency,　the　results　showed　that　returned　sludge　ratio　had　a　deep　effect　on　nitrogen　and　phosphorus　removal,　and　the　distribution　proportion　of　retuned　sludge　and　THR　in　the　pre-zone　had　a　certain　influence　on　phosphorus　removal　but　had　a　little　influence　on　nitrogen　removal.　And　the　optimal　performance　was　when　the　returned　sludge　ratio　was　100%　to　125%,　the　distribution　propotion　was　3　to　7,　and　THR　in　pre-zone　was　1.9　h.　When　ρTN　and　ρTP　in　the　effluent　were　lower　than　15　mg/L　and　2.5　mg/L,　respectively,　TN　can　be　discharged　within　the　standard,　but　the　effect　of　TP　removal　in　effluent　was　not　good.