Recycling　ratio　of　mixed　sludge　and　properties　of　raw　water　(such　as　pH,　turbidity　and　organic　matter　concentration)　were　systematically　investigated　to　optimize　coagulation　efficiency　in　current　study.　It　was　found　that　the　appropriate　recycling　ratio　of　mixed　sludge　was　6%,　effective　initial　turbidity　were　below　45.0　NTU,　and　optimal　pH　for　dissolved　organic　matter　and　turbidity　removal　was　6.5-7.0　and　8.0,　respectively.　Residual　dissolved　alum　(RDA)　in　treated　water　met　the　drinking　water　quality　standard　(＜0.2　mg/L).　Coagulation　efficiency　and　RDA　was　not　negatively　influenced　by　organic　matter　concentration　of　1.104-3.354mgDOC/L.　Under　above　condition,　sludge　reuse　process　could　be　significant　for　the　low/temperature　and　low　turbidity　water　treatment.