Abstract: Concentrations, distribution and accumulation of heavy metals in the sediments of Hulun Lake were investigated. The highest value for heavy metals concentration in sediments before the modern industrialization of the world and grade criteria of the National Standard for soil environmental quality were used to analyze the accumulation coefficient and Potential Ecological Risk (PER) coefficients for heavy metal. The PER index for each sample location was also discussed. The method for evaluation PER index presented by Hakanson was applied to assess the ecological risk. The results showed that the distribution of seven kinds of heavy metals content didn’t reveal the regional distributive characteristics and the differential of space distribution was small. However, Zn, Cr and Cu have the same trend, that the concentrations are higher in northeast and southwest parts of Hulun Lake than those at the entrance of lake for Xinkai River, Wuerxun River and Kerulen River. When the highest value for heavy metals concentrations in sediments before the modern industrialization of the world were taken as reference, the accumulating order of these heavy metals is: Pb>Zn>Cd>Cu>As>Cr>Hg and the order of pollution level is Cd>As>Pb>Cu>Hg>Cr>Zn but most of them were in the low risk states. When the grade criteria of the National Standard for Soil Environmental Quality worked as reference, the accumulating order is Cd> Zn > Cu >As>Pb>Cr>Hg and the order of pollution level is Cd>As> Hg >Cu> Pb >Cr>Zn. Cadmium (Cd) was the potential impact element of the ecological environment of Hulun Lake.