To clarify polycyclic aromatic hydrocarbons (PAHs) contamination characteristics in Lake Chaohu, 27 surface sediment samples from different locations in the lake were collected in 2010. Concentrations of 14 kinds of PAHs measured by HPLC were identified as priority pollutants by the US EPA. The total concentration of PAHs ranged from 116.0 to 2832.2 ng/g dry weight, with an average value of 898.9 ± 791.0 ng/g dry weight. The profiles of PAHs showed that 5- and 6-ring PAHs were predominant, which accounted for 32%-58% of the total, respectively. A good correlation between TOC content and the total PAHs concentration was observed. Based on Anthracene/(Anthracene + Phenanthrene) and Benzo (a) anthracene/(Benzo (a) anthracene + Chrysene) ratios, PAHs originated largely from the high-temperature pyrolytic process. Risk assessment indicated that the sediment in Nanfei River was most likely to pose biological impairment, while low toxicological risk of PAHs was found in other sampling sites.