Abstract: Reservoir sedimentation is important information for hydro-plant running and management.However,the original hydrological stations sections were submerged because of cascade hydropower development,and there is a lack of sediment observation data of in-out reservoir for sedimentation calculation.This paper provides a more accurate calculation method to estimate cascade reservoirs deposition.Taking Xiaowan reservoir for example,we compared historical rainfall data with data in 2015 within the reservoir catchment area,and selected sediment transport rate when the rainfall data are very close to 2015.Then suspended sediment loads at the in-out cross-sections of reservoir could be calculated based on the historical sediment transport rate.Meanwhile,Brune model was employed to calculate sediment trapping efficiencies of cascade reservoirs.Finally,we calculated that the sedimentation volume of Xiaowan reservoir area in 2015 is 11.45106 t.The results could provide theory basis for water-sediment schedule and safe operation of reservoir.The methodology and results in this paper can provide technical reference for calculation of annual sedimentation volume of other reservoirs.