Sludge　aggregation　and　biofilm　formation　are　the　most　effective　approaches　to　solve　the　washout　of　anammox　microorganisms.　In　this　study,　the　structure　and　composition　of　EPS　(extracellular　polymeric　substances)　were　investigated　to　elucidate　the　factors　for　the　anammox　aggregation　property.　Anammox　sludge　taken　from　18　lab-scale　and　pilot　scale　reactors　treating　different　types　of　wastewater　was　analyzed　using　EEM-PARAFAC　(excitation　emission　matrix　and　parallel　factor　analysis),　FTIR　(Fourier　transform　infrared　spectroscopy)　and　real-time　PCR　combined　with　multivariate　statistical　analysis.　The　results　showed　that　slime　and　TB-EPS　(tightly　bound　EPS)　were　closely　related　with　water　quality　and　sludge　morphology,　and　could　be　used　as　the　indicators　for　anammox　microbial　survival　ability　and　microbial　aggregate　morphology.　Furthermore,　slime　secreted　from　anammox　bacterial　cells　may　be　exhibited　higher　viscosity　to　the　sludge　surface　and　easily　formed　the　gel　network　to　aggregate.　Large　amounts　of　hydrophobic　groups　of　protein　in　TB-EPS　promoted　the　microbial　aggregation.　The　mechanisms　of　anammox　aggregation　explored　in　this　study　enhanced　the　understanding　of　anammox　stability　in　wastewater　treatment　processes.