Abstract:12L pyrex bottle experiments were applied to investigate the geosmin production and distribution of Anabaena sp. under eutrophic condition. Geosmin produced by Anabaena sp. increased with the increasing Anabaena sp. cells numbers and the highest concentration recorded was 626ng/L,which was significantly above the perceptive concentration of human with about 10ng/L. Geosmin production was not synchronous with cells growth, and the highest concentration of geosmin was observed 76h earlier before the biomass of Anabaena sp. cells reached the highest point.Geosmin was found to be enriched in cell matrix rather than in medium that about 85%~95% of total geosmin was concentrated in cell. The mud began to release nitrogen since the beginning of culturing and lower nitrogen concentration would induce the synthesis of geosmin using the isoprenoid precursors rather than the demand of chlorophyll accumulation. When the nitrogen concentration was sufficient in medium, the geosmin concentration could be calculated by monitoring the chlorophyll concentration since the geosmin/chlorophyll ratio would reach a stable value at 0.0015.