The　influence　of　ultrasound　energy　densities　on　dewaterability　of　drinking　water　treatment　sludge　and　the　involved　influencing　factors　was　investigated.　The　dewaterability　of　sonicated　sludge　was　improved　at　relatively　low　energy　densities　of　0.03　and　1.0W/mL　in　less　than　10minutes.　However,　at　relatively　high　energy　densities,　the　dewaterability　of　sludge　was　deteriorated　regardless　of　ultra-sonication　time.　The　content　of　solubilized　organic　matter　in　the　supernatant　of　sonicated　sludge　was　increased.　Additionally,　the　floc　characteristics　changed　obviously　and　the　dewaterability　got　worse　as　the　energy　density　increased.　At　lower　energy　densities　of　0.03　and　1.0W/mL,　the　dewaterability　of　sludge　was　not　correlated　with　solubilized　organic　matters　and　floc　characteristics　of　sonicated　sludge.　However,　at　a　high　energy　density　of　5W/mL,　the　dewaterability　was　significantly　related　to　solubilized　organic　matters　and　Zeta　potential　of　sludge.　©　2017,　Editorial　Board　of　China　Environmental　Science.　All　right　reserved.