The heavy metal concentrations (Cu, Pb, Zn, Cd and Cr) in sediments from core XJ2 in Lake Xijiu, Taihu Basin were investigated, and the characters of their temporal distributions were studied on basis of geo-chronological results. Approach of the potential ecological risk assessment proposed by Hakanson was applied to investigate the history and the relative potential ecological risks of heavy metal contamination of lacustrine sediments. The results showed that the sediments were polluted by Cd element far more serious than the rest four elements, so that Cd element was the main factor in heavy metal contamination. From the early 1900s, the heavy metal contamination of sediments and the potential ecological risks increased remarkably. The most serious period, when the contamination of all the five heavy metals reached their “very high” level, was during the middle 1990s. The indexes of potential ecological risk dropped afterwards because a result from the adjustment of industrial structure and closing of some heavy contamination factories by local government, although the contamination conditions and the potential ecological risk were remaining at the “very high” level in 2004.