The　high-rate　contact　stabilization　(HiCS)　process,　a　variant　of　high-rate　activated　sludge,　has　gained　attention　for　its　superior　energy　recovery　and　enhanced　biosorption　capabilities.　The　need　for　efficient　energy　recovery　in　HiCS　necessitates　a　high　settling　efficiency　to　minimize　resource　loss　due　to　endogenous　sludge　consumption.　However,　the　low　sludge　retention　time　(SRT)　required　for　HiCS　can　significantly　affect　sludge　floc　stability　and　flocculation　performance,　warranting　a　deeper　analysis　of　the　factors　influencing　these　characteristics.　This　study　investigates　the　impact　of　SRT　reduction　on　sludge　performance,　focusing　on　energy　potential,　viscoelasticity,　and　critical　pressure.　The　analysis　was　conducted　using　rheological　tests,　contact　angle　measurements,　zeta　potential　analysis,　Fourier　transform　infrared　spectroscopy,　XDLVO　theory,　and　the　PARAFAC　model.　Results　indicate　that　due　to　the　contribution　of　hydrophobicity,　the　HiCS　system　maintained　the　large　flocs　morphology　of　the　sludge　even　when　the　SRT　was　maintained　for　2d.　However,　a　combination　of　aerobic　microbial　activity,　high　concentrations　of　loosely　bound　extracellular　polymeric　substances,　and　the　presence　of　the　filamentous　bacterium　Thiothrix　contributed　to　reduced　flocculation　performance.