Major　bloom-forming　organism　is　the　species　Microcystis　aeruginosa　which　produces　hepatotoxin　microcystin　into　water　and　it　is　harm　to　aquatic　organisms　and　humans.　Ultrasound　is　an　environment-friendly　technology　and　inhibits　the　growth　of　algae　effectively.　First　of　all,　the　effect　of　ultrasonic　frequency,　power　density　and　irradiation　time　on　Microcystis　aeruginosa　through　single　factor　experiments　was　studied.　Then　the　optimized　values　of　the　three　parameters　were　determined　by　Box-Behnken　model　of　response　surface　design.　Results　showed　that　the　removal　efficiency　of　chlorophyll-a　reached　to　(99.33　±　0.02)　%　after　sonication　for　24　s　at　580　kHz　and　0.089　W/mL.　Ultrasonic　technology　can　remove　Microcystis　aeruginosa　in　water　effectively.　Ultrasonic　irradiation　Algae　removal　Microcystis　aeruginosa　Response　surface　design.　This　work　was　financially　supported　by　the　National　Natural　Science　Foundation　of　China　(51308123),　the　Scientific　research　Foundation　in　Fuzhou　University　(2013-XY-25)　and　Fund　for　Fostering　Talents　of　Fuzhou　University　(XRC-1266).