To investigate the occurrence characteristics and bioavailability of heavy metals (Cd, Cr, Cu, Zn, Ni and Pb) in the sediments of Lake Gehu, total content, speciation and bioaccumulation of heavy metals were analyzed. Results showed that distribution of six heavy metals in the surface sediments indicated the highest degree of contamination in the north region, followed by the south region, and the lowest in the central region. Ni, Cu, Zn and Pb contents were significantly higher than background values, which were 4.77, 3.89, 2.96 and 2.76 times higher than background values, respectively. Total heavy metal contents were significantly correlated with contents of clay particle. Speciation analysis of heavy metals showed that bioavailability fraction (sum of acid-extractable, reducible and oxidizable fractions) followed a descending order as:Cd >Cu >Zn >Pb >Ni >Cr. Bioavailability fraction contents of Cd, Cu, Zn and Pb were 84.15%, 78.47%, 76.50% and 78.47% of the total contents, respectively, which showed a relatively high potential ecological risk. Cu and Zn contents accumulated in Bellamya aeruginosa were significantly higher than other metal elements contents. Correlation analysis indicated that only Cr and Pb contents accumulated in Bellamya aeruginosa had significant correlation with bioavailability fraction contents; it turned out that the heavy metals contents accumulated in organism were not only related to the bioavailability fraction contents, but also related to total heavy metals contents in sediments. Therefore, it is necessary to consider total contents and bioavailability of heavy metals contents when we evaluate ecological risk of heavy metals in Lake Gehu.