Water　blooms　caused　by　blue　and　greet　cyanobacteria　has　been　shown　to　be　hazardous　to　both　animals　and　humans.　Ultrasonic　algae　removal　technology　can　be　good　for　controlling　algae　growth　by　appropriate　power,　frequency　and　irradiation　time.　First　of　all,　the　approximate　ranges　of　the　ultrasonic　parameters,　frequency,　power　and　irradiation　time,　were　estimated　with　single　factor　experiments.　Then　the　optimized　values　of　the　three　parameters　were　determined　by　central　composite　design　of　response　surface　design.　Results　showed　that　the　removal　rate　of　chlorophyll-a　reached　to　64.1　%　after　the　irradiation　for　7　min　by　ultrasonic　of　77　kHz　and　100　W.　Ultrasonic　technology　can　remove　Chlorella　pyrenoidosa　in　water　quickly　and　effectively,　so　as　to　achieve　the　purpose　of　water　purification.