Streaming　current　technique,　fluctuation　of　transmitted　light　technique,　molecular　weight　distribution　and　XAD　resin　adsorption　technique　were　used　to　study　the　mechanism　of　natural　organic　matter　removal　by　potassium　permanganate　composite(PPC)　enhanced　coagulation.　Results　showed　that　natural　organic　matter　removal　efficiency　increased　13%　by　0.75　mg/L　potassium　permanganate　composite　enhanced　coagulation　compared　with　that　of　alum　coagulation　alone.　Streaming　current　indicated　that　potassium　permanganate　composite　decreased　the　organic　matter　stability　by　reducing　the　surface　negative　charge,　and　the　SC　value　increased　from　55.2　to　61.4,　69.6　and　87.0　by　addition　of　0.50,　0.75　and　1.0　mg/L　PPC.　Coagulation　index　R　indicated　both　nascent　manganese　dioxide　and　subsidiaries　played　an　important　role　in　potassium　permanganate　composite　enhanced　coagulation　process.　Potassium　permanganate　composite　enhanced　coagulation　increased　the　removal　efficiency　of　lower　molecular　weight　and　hydrophilic　organic　matter　compared　with　alum　coagulation,　and　hydrophilic　organic　matter　can　be　reduced　from　1.9　mg/L　to　1.32　mg/L　by　the　addition　of　0.75　mg/L　potassium　permanganate　composite.