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Reservoirs, as artificial lakes, suffer from silting inevitably since being constructed, the sediments from surrounding environment can provide a continuous record of environmental change. Shilianghe Reservoir, the largest artificial lake in Jiangsu Province, was constructed in 1959, and plays an important role in flood control, irrigation, water supply, and so on. Nevertheless, the silting situation of the reservoir is also quite serious. In this paper, the grain-size distribution of core from Shilianghe Reservoir and its response to environmental changes were studied. It is due to two driving factors; climate variability and human activities. Based on the analysis of the grain size distribution data, the sediments were mainly composed of clayey silt and silty clay with a clear tendency of upward fining. But a grain-size peak appeared at 86 cm, and the sand proportion was also very big, indicating that hydrodynamic force was stronger. There was a consistent trend of change between sediment record in Shilianghe Reservoir and historical precipitation in the basin. According to the dating mark of 137Cs, it can be determined primarily that the abnormal grain-size at 86 cm reflected possibly the rainstorm and flood event occurring in 1970. Human activities reduced the hydrodynamics of depositional environment. Hydraulic projects are direct human activities, and land use/cover changes are indirect human activities. It turned out that sediment yield and sediment load were more and more less, and sedimentation rate showed a decreasing trend. Furthermore, sediments tended to become smaller and had better sorting property. [ABSTRACT FROM AUTHOR]