Abstract: As an emerging pollutant, microplastics have spread all over the marine environment. Studies have shown that the marine sedimentary environment is the sink for marine microplastics, The Changshan Archipelago (Changdao) are located at the throat of the Bohai Sea and belong to a typical island ecosystem. In recent years, the coastal area of Long Island has been affected by human factors such as the construction of breeding ponds and port terminals, and the ecological environment is relatively fragile. In this study, the sediments of Changshan Archipelago were collected, and the microplastics in these sediments were analyzed by microscope observation and fourier transform infrared spectroscopy. The results showed that the abundance of microplastics in the Changshan Archipelago sediments ranged from 133.14 to 499.82 N/kg, with an average abundance of 252.59 N/kg. The size of microplastics is mainly <500 μm, accounting for more than 70% of the total number of microplastics; the shape of microplastics is mainly granular, followed by fragments, fibers and small spheres; the color of microplastics is mainly transparent. The polymer type of plastic is mainly cellophane, followed by polyethylene, polyethylene terephthalate, cellulose, etc. Because Changdao is located at the intersection of the Yellow Sea and the Bohai Sea, the overall hydrodynamic exchange capacity is well. Although the water mobility of the southern waters of Changdao is weaker than that of the northern waters, and the southern waters are closer to the rivers entering the sea, and are more affected by the input of land sources, the abundance of microplastics in the sediments of the southern water of Changdao is not significantly higher than that of the northern water. This study provides a scientific basis for the scientific assessment and management of microplastic pollution in the marine ecological environment of Long Island.