Abstract: In recent years, research on microplastics pollution in the marine environment has been increasing, but studies on microplastics in water bodies and sediments of the bay under the influence of high-intensity human activities are still rarely reported. In this study, the pollution characteristics of microplastics in the wayer and sediments of Sanggou bay were investigated in December 2017, after the harvest of large-scale aquaculture, with the aim to study the effects of aquaculture activities and hydrodynamics on pollution characteristics and spatial distribution of microplastics in the bay. The results showed that the types of microplastics in the water and sediments of Sanggou bay were mainly fibers, fragments, films, foams and particles. The microplastic abundances in the water and sediments were 1.8~31.2 N/L, 31.2~1246.8 N/kg, respectively. The average particle sizes of microplastics in water and sediments were 0.51 ±0.20 mm and 1.54 ±1.02 mm, respectively. The results of spatial distribution of microplastics in Sanggou bay showed that the high abundance area mainly appears in the inshore waters, and the abundance of microplastics tends to decrease from the inner areas of estuary to the outshore areas. The heterogeneity of microplastic abundance and spatial distribution in Sanggou bay is mainly affected by human activities such as aquaculture, living and shipping, as well as hydrodynamics. In the future, fine sampling and analysis are needed to fully understand the temporal and spatial distribution of microplastics pollution in the bay areas.