Abstract: Plastic pollution is one of the most prominent marine environmental problems. At present, the research on marine microplastics is mainly based on laboratory experiments and field measurements, while there is relatively little numerical simulation research on their migration distribution. This paper uses MIKE3 three-dimensional hydrodynamic module coupled with ECO Lab module and ABM module in order to simulate the migration and distribution characteristics of floating and suspended microplastics in Jiaozhou bay under both wind and current, then the impact of reclamation-induced coastline evolution on the distribution of microplastics is investigated. The results show that the floating microplastics accumulate in large quantities in the northeast of Jiaozhou bay, Qianjiao waterway, Huangdaoqian bay and Haixi bay, and are not easy to be transported out of the bay along with flood and ebb current. For suspended microplastics, there are multiple high-concentration areas in Huangdaoqian bay, Haixi bay and near the Jiaozhou bay mouth. Under the influence of reclamation in the past 50 years, the concentration of both floating and suspended microplastics in the central and near the mouth of Jiaozhou bay, Qianjiao waterway, Huangdaoqian bay, Haixi bay and Dagang has been continuously increasing.