There　is　limited　research　on　partial　nitrification　anammox（PNA）coupled　with　membrane　bioreactor（MBR），especially　the　lack　of　membrane　fouling　behavior　of　this　coupled　system.　In　this　study，the　cake　and　bulk　sludge　from　a　continuous　flow　PNA-MBR　were　analyzed　and　compared.　The　results　showed　that　the　average　particle　size　of　the　cake　sludge　was　larger　than　that　of　the　suspended　sludge，and　the　EPS　extracted　from　cake　sludge　had　higher　concentration　of　protein，polysaccharide，and　humic　substances.　Moreover，The　EPS　extracted　from　cake　sludge　had　looser　protein　secondary　structure　and　stronger　surface　hydrophobicity.　Dead-end　membrane　filtration　experiments　showed　that　membrane　fouling　caused　by　the　EPS　extracted　from　cake　sludge　was　more　serious　than　that　of　suspended　sludge.　The　effect　of　humic　substances　on　normalized　flux　was　significant.　Microbial　community　analyses　showed　that　the　microbial　community　exhibited　higher　diversity　in　cake　sludge.　Additionally，the　relative　abundance　of　Patescibacteria　and　norank_f__norank_o__norank_c__SJA-28　was　higher　in　cake　sludge　than　that　in　suspended　sludge，implying　a　higher　membrane　fouling　potential.　©　2025　Science　Press.　All　rights　reserved.