Pre-coagulation　enhanced　by　KMnO4　before　ultrafiltration　(KCUF)　was　compared　with　normal　pre-coagulation　by　alum　(CUF)　in　the　ultrafiltration　of　water　from　the　Songhua　River,　China.　The　transmembrane　pressure　(TMP)　with　KCUF　was　much　lower　than　that　when　alum　alone　was　used.　With　KCUF　a　slower　increment　of　TMP　occurred,　even　under　conditions　of　high　river　water　turbidity.　The　results　also　showed　that　the　removal　of　COD,　UV254　and　TOC　was　appreciably　higher　after　adding　0.5mg/L　KMnO4　compared　with　CUF.　Although　assimilable　organic　carbon　(AOC)　was　increased　by　permanganate　treatment,　the　AOC　of　the　permeate　from　KCUF　was　nearly　the　same　as　that　from　CUF,　showing　that　the　cake　layer　on　the　surface　of　KCUF　membrane　could　adsorb　small　molecules　more　effectively　than　that　of　CUF.　This　result　was　confirmed　by　the　apparent　molecular　weight　(MW)　distribution　measured　by　size　exclusion　chromatography　(SEC).　It　was　shown　that　flocs　formed　by　KMnO4　and　alum　were　larger　than　those　formed　only　by　alum,　causing　higher　removal　of　flocs　and　higher　permeation　flux.　Lower　NOM　was　found　in　the　permeate　from　the　KCUF　systems　because　oxidation　and　adsorption　of　organic　matter　on　the　flocs　occurred.　The　membrane　was　partly　clogged　by　organic　matter　or　other　materials　including　some　small　flocs.