Abstract: With the increase of sewerage discharge, PAHs pollution has become more serious.3, 4-benzo (a) pyrene, 9, 10-dimethylanthracene, 3-methylphenanthrene are carcinogenic PAHs in ocean.Sea cucumber (Apostichopus japonicus) is a widely cultured economic species in the coast of China.Therefore, it is particularly important to study the bioaccumulation of PAHs by sea cucumber.The semi-static two-compartment kinetic model was used to simulate the bioaccumulation experiment of 3, 4-benzo (a) pyrene, 9, 10-dimethylanthracene, 3-methylphenanthrene by Apostichopus japonicus.The bioaccumulation kinetics parameters of 3, 4-benzo (a) pyrene, 9, 10-dimethylanthracene, 3-methylphenanthrene were achieved by nonlinear curve fitting.The results showed that sea cucumber has ability to accumulate 9, 10-dimethylanthracene, 3, 4-benzo (a) pyrene and 3-methylphenanthrene.The enrichment ability and rate of sea cucumber to the three polycyclic aromatic hydrocarbons increase with the increase of the concentration of the three polycyclic aromatic hydrocarbons in the seawater.The absorption processes of PAHs conform to two-compartment kinetic model under the conditions of 3, 4-benzo (a) pyrene 5 μg/L, 9, 10-dimethylanthracene 10 μg/L and 3-methylphenanthrene 100 μg/L concentrations.The BCF of the three PAHs absorbed by sea cucumber are in the order of 9, 10-dimethylanthracene 148.3>3, 4-benzo (a) pyrene 126.9 >3-methylphenanthrene 88.0 at the concentration of 5 μg/L.