Transfer and fate of naphthalene (PAHs) in multi-medium of Songhua River was studied. A level III fugacity model was applied to calculate the multi-interface transfer flux and concentration distribution of naphthalene in Songhua River under steady-state assumptions. The results indicated that soil was the largest storage of naphthalene, accounting for 40％ of the total amount of residual. In air, water, soil and sediment, the concentrations of naphthalene were 3.58×10-6 μg·g-1, 0.142 μg·L-1, 5.28×10-4 μg·g-1 and 3.62×10-3 μg·g-1 respectively. The reliability of the model was verified by the coincidence of the calculated and the measured concentration in the same period.