The metal contents in the sediments are influenced not only by human pollutants，but also by grain size and mineral composition of the sediments, which should be evaluated in the study of heavy metal. The metals contents and their correlations with grain size in sediments of core MS from Lake Taihu are studied in this paper in order to evaluate the grain size effects on metals contents. The metals in core MS can be classified into two categories according to their variation characteristics. Al, Fe，K etc belong to one category, the contents of which are high in the middle-lower section of the sediment core and low in the upper section; Na belongs to the other category, the variation of its content is opposite with the first category. According to the correlations of the metals and grain size, clay content was selected as the normalization component of metals. After normalized by the clay content, the metals contents take on consistent variation along the sediment core. The analysis results show that the metals contents in Core MS are influenced mainly by grain sizes composition and the normalization of metals content must be taken during the study of metals variation and pollution evaluation.