C.S.G is a material made by adding cement and water to rock-like material such as riverbed gravel or excavation muck that can be obtained easily near dam si. Recently, the use of C.S.G is gradually increasing as the construction material for dam, road, revement and so on. Commonly, the strength characteristics of C.S.G is affected by various influence factors such as grade, unit cement, age and water contents. In this study, a series of compaction test and unconfined compressive strength test were performed to investigate the relationship between a strength and influence factors such as three kinds of gradation, age, unit cement and water contents with riverbed gravel in Hwa Buk dam. The results show that strength Properties of C.S.G is variously affected by these influence factors. Especially, gradation and water contents are found to be very important factors fur determining the strength of C.S.G material. And, from the results of experimental study, the correlation equations between uncompressive strength and these factors are proposed.