The release of nutrients caused by the algae detritus decomposition has been widely studied, however, little is known about the mechanism of pollutants release induced by the interaction of accumulated algae detritus with sediments. In order to simulate the release characteristics of nutrients after different density algal debris settled on sediments on the summer temperature condition, sediments cores were sampled from Yuqiao Reservoir Watershed and cultured with five density gradients addition treatments and control without algal detritus under constant temperature condition (27±1℃). Results showed that algal detritus enhanced oxygen consumption and nitrate reduction, and overlying water in addition treatments reached anaerobic condition after the incubation time of 18 hours. The concentration of dissolved organic carbon (DOC) in each addition treatment increased in three hours and the value of SUVA₂₅₄ varied between 0.54-1.74 L/(mg·m), suggested that DOC was mainly derived from algal detritus decomposition. The concentrations of dissolved organic nitrogen(DON), ammonia nitrogen and phosphate in five addition treatments increased gradually with the release rates of 4.44 mg/(L·h), 0.20 mg/(L·h) and 0.025 mg/(L·h), respectively, and was 21.73, 1.76, 67.58 times of the release rates of control, respectively. DON was the main form of dissolved total nitrogen(DTN). Subsequently, the decrease of DOC/DON at the end of incubation suggested that algal detritus and sediments organic matter were not completely mineralized in which DOC took priority over DON being consumed by microorganisms. In general, accumulated algal detritus strengthen benthic oxygen demand and then accelerate the microbial geochemical cycle of nutrients and DOC between the interface of water and sediment.