Abstract: Nitrogen release characteristic of Dianchi lake sediment and the nitrogen nutrients concentration of overlying water body was studied through simulating cultivation. The results indicated that under disturbed sediment released N nutrients to overlying water body markedly. The dead cells of phytoplankton could promoted organic nitrogen of sediment mineralization. The amount of nitrogen nutrients released of sediment was correlation with the amount of dead cells of phytoplankton being deposited. Ammonia was the main form of the nitrogen nutrient being released into overlying water body, and it was transformed to nitrite soon. And then nitrite was transformed to nitrate.