The　effects　on　algae　removal　imposed　by　ultrasound　technology　employing　different　combinations　of　parameters,　including　frequency,　power　and　irradiation　time,　were　estimated　using　response　surface　methodology.　This　technology　was　applied　in　the　backwater　area　of　Pengxi　river　in　the　three　Gorges　Reservoirs.　Results　showed　that,　the　algae　removal　rate　by　ultrasound　was　64.1　%,　at　an　optimal　frequency　of　45　kHz,　input　power　of　60　W　and　irradiation　time　of　48　s.　After　2　h　of　ultrasound　irradiation　on　the　500　m(2)　study　field,　the　algae　density　dropped　from　(1.10　+/-　0.02)　x　10(7)　to　(2.1　+/-　0.1)　x　10(6)　cells/mL.　Chlorophyll-a　concentration　dropped　to　13.8　%　of　its　initial　amount　algae　were　effectively　controlled.　Ultrasound　technology　is　concluded　to　be　effective　for　algae　removal　and　can　thus　be　applied　to　algal　blooms.