In megathermal climate, a great amount of blue green bloom (mainly consisted of microcystis) is observed to appear in some freshwater lakes of China, i. e. Chaohu Lake. The bloom contains protein, amino acid, fat and some other nutriuan substances. Ln this paper, the amino acid compositions and contents in microcystis were first determined. After extraction and isolation, the phycobiliproteins are purified and further identified i based upon the algal biliproteins, uv-vis absorbance spectrum. The results obtained are satisfactory, which provides an experimental basis for further exploitation and utilization of bloom in Chaohu Lake.