Abstract: In order to study the distribution of polycyclic aromatic hydrocarbons (PAHs) in the sediment-seawater system, 16 kinds priority control PAHs in the sediments and seawater from 9 sampling points at the Xiangshan port were analyzed in January 2017. The source analysis and diffusion equilibrium were conducted by isomerism ratio method and fugacity approach. The concentrations of PAHs in the sediments ranged from 17.51×10^-9～84.41×10^-9, mainly high ring PAHs, and the pollution level was minor polluted. The PAHs in the sediments primarily came from high temperature combustion sources. The ranges of PAHs in the surface seawater, intermediate seawater and bottom seawater were 41.78～105.72 ng/L, 41.51～106.34 ng/L and 9.18～145.17 ng/L, respectively, which low ring PAHs were the most abundant compounds. The sources of PAHs in seawater originated mainly from oil leakage and oil combustion. The fugacity fraction was calculated to judge the diffusion behavior of PAHs. Nap, Ace and Flo were released from sediments to seawater. Acy, Phe, Ant and Pyr were close to the dynamic equilibrium in sediments and seawater. Flu, BaA, Chr and BbF were mainly diffused from seawater to sediment.