Marine microplastics in coastal regions, where human activity is intense, have attracted widespread attention. In this paper, the distribution, composition, and seasonal variation of marine microplastics in oysters and sediments of Zhanqiao Pier are studied. The results showed that the variation trend of microplastic abundance in oysters and sediments is consistent, with the tendency that summer > winter > autumn. In all three seasons, the abundance of microplastics in oysters was significantly higher than that in sediments, which was 3~4 times that in the sediment. Overall, Microplastics in oysters and sediments are mainly fibers, <1 mm, with no obvious seasonal change. In general, the color of microplastics in oysters and beach sediments is mainly transparent and blue. Micro-FTIR shows that the polymers of microplastics include polyester, acrylic, rayon, cellulose, and polypropylene-polyethylene copolymer. Based on the consistency of the abundance of microplastics in oysters and sediments with seasonal changes and the similarity of the physical characteristics of microplastics, it is suggested that oysters should be used as marine microplastics indicators in the Qingdao coast. This study can provide a reference for the risk assessment and monitoring of marine microplastics pollution in Qingdao inshore marine products.