Extracellular　polymeric　substance　(EPS)　is　a　key　factor　affecting　the　property　of　activated　sludge.　In　this　study,　the　components　of　EPS　in　activated　sludge　of　municipal　wastewater　treatment　plants　(WWTPs)　were　quantified,　and　the　correlations　of　EPS　components　to　wastewater　characteristics　and　operational　conditions　were　analyzed.　Results　indicated　that　protein　was　the　main　constituent　accounting　for　25%~63%,　followed　by　humic　acid　with　21%~50%.　DNA　and　polysaccharide　were　the　least.　Sludge　settleability　and　particle　size　distribution　was　obviously　different　in　two　wastewater　treatment　plants　even　though　the　same　process　(A2O)　was　applied.　According　to　the　Pearson　analysis,　there　is　no　correlation　between　EPS　content　and　sludge　volume　index　(SVI)　or　particle　size　distribution　under　normal　and　limited　filamentous　bulking　conditions.　Yet　the　content　of　DNA　and　humic　acid　both　positively　correlated　with　SVI.　The　hydraulic　retention　time　(HRT)　of　the　process　negatively　correlates　with　EPS　content,　but　the　content　of　organic　matters　in　wastewater　had　no　effect　on　EPS　and　components.　The　content　of　polysaccharide　significantly　correlated　with　biological　nutrients　removal,　which　could　be　used　as　carbon　sources　for　biological　nutrients　removal.　Sludge　retention　time　(SRT)　affected　the　ratio　of　protein　to　polysaccharide.　Therefore,　wastewater　characteristics,　process　types　and　operational　conditions　affected　the　components　and　content　of　EPS　and　further　affected　the　performance　of　WWTPs.　©　2017,　Science　Press.　All　right　reserved.