Effect of UV - B radiation on the feeding behaviour of marine zooplankton is important to assessing the health harm of marine ecosystem due to the gradually enhanced UV - B radiation in air. However, there are a few studies on this topic. The feeding behavior of the rotifer, Brachionus plicatilis, under the treatment of UV - B radiation on five species of microalgae, i. e. , Chlorella sp. ,Tetraselmis chuii, Isochrysis galbana Park 8701, Chaetoceros muelleri Lermumerman, and Nitzschia clostertum, was studied. The results showed that the filtering and feeding rates of the rotifer decreased significantly with the dose increase of UV - B radiation when fed with five species of microalgae respectively (P ＜ 0.05 ) which indicates UV - B radiation inhibits the feeding activities of the rotifer on microalage. The mixed culture experiments shows the rotifer preferred to feed Chlorella sp. , then C. muelleri, I.galbana, N. clostertum and T. chuii in turn if without UV - B radiation. Under the highest dose of UV - B radiation treatment (2.70 kJ/m2) , the rotifer preferred to feed C. muelleri, then Chlorella sp. , N. clostertum, I. galbana and T. chuii in turn.Chlorella sp. , I. galbana and C. muelleri became the more favorite foods of the rotifer while T. chuii and N. clostertum became less favorite foods. The change of feeding rate and feeding selectivity of zooplankton driven by the enhanced UV - B radiation will lead to the change in the structure of phytoplankton community.