The　kinetics　of　nitrification　inhibition,　the　components　of　polymeric　substances　on　extracellular　and　oxygen　uptake　rate(OUR)of　partial　nitrification　sludge　were　studied　at　various　concentrations　of　phenol　that　was　served　as　short-term　toxic　inhibitor.　The　results　showed　that　rate　of　ammonia　nitrification　reduced　by　37%　due　to　inhibition　effect　of　phenol　on　the　ammonia　oxidation　bacteria.　Under　low　phenol　concentrations(-1),　it　followed　Monod＇s　kinetics　for　single　molecule　inhibition,　indicating　that　was　a　kind　of　reversible　inhibition,　and　OUR　achieved　at　20-25　mg　O2·L-1·h-1　after　the　rescission　of　inhibition.　The　inhibition　constant(52.871　mg·L-1)of　mixed　sludge　system　used　in　this　study　was　far　larger　than　that　of　an　enrichment　nitrifier　culture.　In　addition,　the　phenol　promoted　the　starting　of　microbial　self　protection　mechanism　that　could　produce　more　extracellular　polymeric　substances(EPS)to　resist　environment　change.　With　the　phenol　concentrations　up　to　135　mg·L-1,　proteins　and　carbohydrate　in　EPS　increased　up　to　87.4%　and　311.7%　respectively.　The　ratio　of　proteins　to　carbohydrates　fell　from　22.1　to　3.80　with　the　increasing　initial　COD/N.　©　2012　All　Rights　Reserved.