Abstract: In order to study the physical and chemical characteristics and distribution of microplastics in the surface water of the Beibu Gulf, 330 μm mesh surface trawls were used to collect microplastics in the surface water at 12 stations. The samples in seawater were digested by ferrous sulfate solution and hydrogen peroxide, and the microplastics were separated by a filter membrane. The size, shape and color of the microplastics were analyzed by stereomicroscope and the composition of the microplastics were analyzed by Fourier transform infrared spectrometer. The results showed that: (1) The average abundance of microplastics in the surface water of the Beibu Gulf was (0.56±1.02) pieces/m³, which was at a medium level compared with other bay areas in the world. (2) The particle size of most microplastics was between 1 mm to 2 mm, accounting for 30.4% of the total microplastics. The main shapes were foam and film, accounting for 62.7% and 15.4%, respectively. The colors were mainly white and translucent, accounting for 68.8% and 16.4%, respectively. The main components of microplastics were polystyrene, polypropylene and polyethylene, which account for 59.8%, 20.9% and 17.6%, respectively. (3) Affected by human activities, river input, prevailing wind and ocean circulation structure, the spatial distribution of microplastics in the surface water of the Beibu Gulf was characterized by higher abundance nearshore than offshore. (4) Based on the characteristics of the shape and composition of the microplastics, it is speculated that the main sources of microplastics in the surface water of the Beibu Gulf were mariculture and marine fishery activities. In summary, the pollution of microplastics in the surface water of the Beibu Gulf is higher in nearshore water than offshore. It is significantly affected by marine fishery activities. It is recommended to strengthen the control of mariculture and marine fishing activities in the Beibu Gulf to prevent and reduce the microplastic pollution.