Abstract: The marine bivalve scallop (Chlamys farreri) was selected as the target organism, and the roxarsone exposed experiments were carried out with the nominal concentrations of 0 mg/L、0.2 mg/L、1 mg/L、5 mg/L、25 mg/L.The biological accumulation and release of arsenic (As) in hepatopancreas, gill, muscle, and mantle were studied.Results showed that:(1) Both in the natural sea and the clean seawater, the sequence of As content in the four tissues was gill > hepatopancreas > mantle > muscle.(2) During the bioaccumulation, the sequence of As content in the tissues was hepatopancreas > gill > mantle > muscle.And during the release, the sequence of the As release rate was gill > hepatopancreas > mantle > muscle.(3) The main pathway for roxarsone entering C.farreri was the ingestion and filter effects of gills.And the main target tissues of As bioaccumulation in C.farreri were hepatopancreas, gill, and mantle.(4) In the present study, the average period of bioaccumulation and release of As in C.farreri was 22 days in the bioaccumulation experiments, and 15 days in the release experiments.And meanwhile, there were 2 cycles in the release experiments and then the As content in the scallops tend to be stable.