A heterotrophic nanoilagellate (Kinetoplastida) was separated which feeds on Microcystis cells by endocytosis.Its morphological characters were observedd by the optical microscope and confocal scanning light microscope.The eating process could be finished in several seconds (even less than 3 seconds).One flagellate could eal more than ten Microcystis cells at most.The flagellate was single cell protozoo with one, two or four flagella.The flagellate was transparent and without pigments.It appeared to be spherical in shape at most of the time and occasionally they are elliptical or other shape.The spherical flagelltes ate Microcystis cells with low moving velocity, the other flagellates moved faster but diclnt eal Microcystis cells.The flagellate reproduced by equal binary fission and this procedure lasted about 5 minutes.According to the niorf)hological obsmation, the flagellate should be belonged to Sarcoraastigophorea, Zoomastigophorea, Kinetoplastida.The relative activity of protease was greatly unproved after inducing by feeding with Microcrstui cells.The results suggested that the flagellate have strong ability to digest the cells of Microcystis.It could remove 80% of tlie Microcystis cells in less than 20h in our study.The flagellate should be used for ecological control of Microcystis water bloom.To get a large population, the culturing of ihe flagellate was studied.SynechocystLs, Murocrstis, Anabaena, Chiorella, E.coh, yeast cells and yolk, milk powder were used as feed, respectively.Results showed that Syiiechocystis, Microcystis, milk power, yolk and yeast were its favorite foods.Among them, Syiiechocystis and yeast cells were better than others.The flagellate was endurable to low temperature.Even storing at 4℃ more than a month, it could survive aud reproduce as usual.The applicalion of this flagellate to natural ecosystem will be investigated rn futwre research.