Based on the observed concentration of eight PAHs from water of the Songhua River,generalized risk factor and four-step health risk approach were employed to address the ecological and health risk of PAHs to local aquatic ecosystem.The results show that anthracene was the most toxic compound to aquatic organisms both in low-flow period and mean-flow period.The hazard quotient indicates that the ecological risk of 8 PAHs is high in low-flow period,but low in mean-flow period.The concentration of 8 PAHs probably brings risk to human health,but the risk is in an acceptable range of 10 -6-10 -7.The main stream water of the Songhua River is with a certain carrying capacity of PAHs pollution.