To study the pollution characteristic and cancer risk of PAHs in water environment, water and sediment samples were concurrently collected on 13 monitoring sections within the Songhua River Basin. Totally, 6 batches of sampling programs were conducted from 2006 to 2010, including the low water season, the high water season and the icebound season. Water and sediment samples were extracted by liquid-liquid extraction and Soxhlet extraction, respectively. The qualification and quantification of PAHs were analyzed by GC-MS. The compositional pattern of PAHs indicated that low ring PAHs were predominant in water samples, while high ring PAHs dominated in sediment samples. The average total concentrations of 15 PAHs were (73.7±27.8)ng／L and (127±117)ng／g, ww for water and sediment samples, respectively. The concentration of PAHs was lower than those of other rivers in China. Obviously seasonal variation of PAHs concentration was observed in the water environment of the Songhua River. For water samples, the PAHs concentrations in the low water season and the high water season were higher than those in the icebound season. For sediment samples, the PAHs concentrations in the low water season were much higher than those in the high water season. The results of the incremental lifetime cancer risk assessment model indicated that the estimated integrated lifetime cancer risks were less than for 10-6, indicating low level of cancer risk for all age groups.