In recent years, due to the eutrophication of water-bodies, some freshwater lakes in China such as Chaoha I^ake and Taihu Lake have been heavily contaminated by water bloom.In this paper, the mouse assay method was used to detect toxicity of blue-green algae and its extraction such as phycobiliproteins in Chaohu Lake and Taihu Lake, The results show no toxicity to experimental animals, which provided a scientific basis for further exploitation and utilization of bloom in Chaohu Lake and Taihu Lake as feed additive, nutriment, and so on.