Abstract: Research indicates cyanobacteria blooms not only endanger water quality,but also produce neurotoxins and odorous matter. In order to scientifically predict water bloom, and then provide fundamental knowledge on the prevention and control of water bloom and odor, preponderant algae species of cyanobacteria bloom and geosmin odor source multiplied in early spring were identified by means of PCR amplification and gene sequencing technology. The effects of different temperature and light intensity on preponderant algae biomass and geosimin odor yield were also measured respectively under laboratory conditions. The preponderant algae were cultured at three temperatures (16, 26 and 36℃) and three light intensities16, 26, 36 μmol·m^-2·s^-1. The preponderant algae of cyanobacteria bloom was identified as Aphanizomenon gracile, and the strong smell of the eutrophicated lake might come from the geosmin of Aphanizomenon gracile. Laboratory simulation study indicate that the content of Aphanizomenon gracile chlorophyll-a and the yield of geosmin odor became higher at low temperature and high light intensity, indicating low temperature and strong light environment were favorable growth conditions. It was found that the effect of temperature was more significant than light intensity on Aphanizomenon gracile, and the highest yield of the geosmin odor was 6 555 ng·mg^-1 under favorable conditions.