Selecting modern beach in the Xiashan reservoir as the research object, the sediments, sedimentary structures, grain size characteristics, sedimentary units and sequence of the beach have been studied herein. The sediments of the beach are dominated by better sorted fine sand and silt, and distributed on the shoreland of the reservoir as a sheet. The sedimentary structures are characterized by bedding, ripple, dwelling burrow, shell fragment, and plant debris. The grain-size accumulation curve includes three types,which are two-segment type, two saltation sub-populations, that is, one suspended sub-population type and transition section between one saltation sub-populations and one suspended sub-population type. The sedimentary units are composed of sheet sand of the back beach, beach ridge and space between beach ridges. In the vertical, the beach shows obvious inverted sequence, and develops the shore lake muddy sediments, space between beach ridges, beach ridge and sheet sand of the back beach from the bottom to the top. And, the wind and geomorphology are the important factors controlling the formation of the beach in this area. The study on characteristics and controlling factors of modern beach has an important significance for the hydrocarbon exploration of the beach-bar sandbodies. The distribution area of the beach can be forecasted by analyzing the controlling factors, and the beach sandbody with poor physical property and bar sandbody with better physical property can be identified by studying the characteristics of the beach and the bar.