Abstract: The upper layer sediment in the water level fluctuating zone of Three Gorges Reservoir area (TGRA)is studied through an analysis of phosphorous forms and adsorption isotherm curves in the fluctuating zone with wet-drycycles.The result shows that the total phosphorous (TP)content for August would be higher than of May in the over-lying water,while the lowest value is found in November.The max adsorption quantity of phosphorus and the max buffer capacity of soil of sediments increase while their equilibrium phosphorus concentration and reactive desorbed phosphorus drop when sediments alternated from the submerged state to the exposed state,which indicates that phos-phorous fixing strengthens whereas phosphorous releasing weakens in the exposed sediments in summer.Moreover,in the course of being submerged for the first time,sediments phosphorous show an alternation from a source to a sink. During the initial stage of impoundment of Three Gorges Reservoir,phosphorous is being accumulated in the sediment.This phosphorous-enriched upper sediment layer in the water level fluctuating zone will be washed away with reservoir sluicing in the following year.