In　view　of　problems　such　as　the　poor　control　effect　of　combined　sewage　pollution　caused　by　traditional　intercepting　weir　and　the　limited　extension　of　the　urban　drainage　model,　which　needs　a　large　amount　of　basic　data,　this　paper　not　only　studied　the　characteristics　of　mixed-flow　pollution　via　the　urban　drainage　model　but　also　simulated　and　optimized　6　interception　control　strategies　and　proposed　a　water　quality　interception　strategy　based　on　the　pollution　concentration　of　combined　sewage.　The　results　showed　that,　compared　with　the　traditional　interception　weir,　the　interception　control　strategy　of　rainwater　discharge　based　on　the　mixed　pipe　network　model　can　obviously　improve　the　control　rate　of　various　pollutants　and　reduce　the　interception　amount　required　for　pollution　control.　Through　optimization　of　the　interception　based　on　water　quality　control　by　the　combination　of　chemical　oxygen　demand　(COD)　and　NH4-N,　the　interception　rate　was　improved　by　10.9%　to　56.1%　in　contrast　to　the　traditional　interception　weir　and　the　closure　water　volume　was　reduced　by　1432-6154　m(3),　which　effectively　improved　the　reliability　and　economy　of　the　interception.