The decomposition rate of cyanobacterial detritus and the release forms of nitrogen and phosphorus from the decomposing cyanobacterial detritus were investigated experimentally in this paper.Results showed that the content of total nitrogen of cyanobac-terial detritus was 88.56±4.10 mg/g;the decomposition rate of cyanobacterial detritus was high and there was 41.9% dry mass lost in two days.The release rate of total phosphorus of cyanobacterial detritus was faster than total nitrogen, but the increase in concentration of total dissolved nitrogen (TDN) in the water column lasted longer than total dissolved phosphorus (TDP) during the decomposing of cyanobacteria.After the increase in the first four days, the concentration of dissolved inorganic nitrogen (DIN) was kept constant but the concentration of dissolved organic nitrogen (DON) continued to increase.The ammonia was the main form of DIN in the water column, while the concentration of nitrate and nitrite was low during the decomposition.The Urea-N was not the main form of DON released by cyanobacterial detritus because the average percentage of Urea-N was low (3% of DON).The concentration of dissolved inorganic phosphorus (DIP) and dissolved organic phosphorus (DOP) increased in the first four days, and then DOP was transformed into DIP progressively.The present study demonstrated that the decomposition rate of cya-nobacterial detritus is high, with releasing of organic and inorganic nitrogen and phosphorus.The result of present study shed light on understanding of the impact of cyanobacterial blooms on nitrogen and phosphorus cycling of lakes.