Reservior sedimentation and its effect on environment are the most serious world-wide problem in water resources developement and utilization today.Based on the data collected,a brief introduction about the development of dam construction is made.The seriousness of reservoir sedimentation and its effect on hydraulic project and environraentel problem are analysed.The method and experience of prevention and reduction of reservoir sedimentation are presented in this paper.It is benefit to the sediment problem treatment in reservoirs as well as in lakes.