The samples of zooplankton taken from 24 stations of 8 sections in Poyang lake in two seasons, spring and autumn in 1999, were identified. The 150 species of zooplankton was found, the most of which were rotifers. The species number of rotifer was found 96, reached to 64.0% in the total species, which showed that rotifers were preponderant genus. The protozoan took place in the second. The distribution of the quantities of the four genus, Protozoan, rotifer, cladocera and copepoda differed a lot in each stations, those of which No.10, 12, 13 and 23 station were in higher level, more than 100ind/L. The highest level appeared in No.13 station, whose quantities were 1101.60ind/L. The amount of zooplankton changed with seasons apparently, while rotifers fluctuated more. The quantities of rotifer and cladocera were more in spring than in autumn, while protozoan and copepode were just opposite.