Shaanxi province is one of themost serious regions of soil and water loss in China,The soil and water loss leads to heavy sediment concentration in the rivers,the disasters of reservoir sedimentation are very serious.The reservoirsedimentation not only reduces the goals of multiple purpose development but also endangers the safety of the lifeand property of the people in the downstream. This paper elaborates the harmfulness of reservoir sedirnentation andits causes,and proposes the measures of prevention and cure.