The　coagulation-supporting　effect　of　pre-oxidation　of　potassium　manganate　in　the　process　of　coagulation　was　studied　in　this　paper.　The　experimental　results　showed　that　the　coagulation-supporting　effect　of　potassium　manganate　was　obvious.　When　the　dosage　of　potassium　manganate　was　2.0　mg/L,　the　turbidity　removal　efficiency　of　sedimentation　water　was　95.59%.　However,　when　the　dosage　of　Al2(SO4)3　was　8.0　mg/L　without　adding　potassium　manganate,　the　turbidity　removal　efficiency　of　sedimentation　water　was　only　88.61%.　The　neutral　and　weak　alkaline　water　had　good　effect　on　coagulation-supporting　effect　of　potassium　manganate,　except　weak　acid　water.　The　Mn2+　in　the　water　was　helpful　for　potassium　manganate　to　remove　turbidity.　Potassium　manganate　should　be　added　before　adding　coagulant.　Under　the　best　potassium　manganate　dosage,　the　turbidity　removal　efficiency　of　sedimentation　water　exceeded　90.00%　when　the　pre-oxidation　time　was　3　min.　In　addition,　potassium　manganate　had　good　coagulation-supporting　effect　on　high　turbidity　water.