The Pinqing Lake with an area of 23.16 km2 and a length of 39.62 km along the coast is located in Shanwei City of southern China; it is the biggest coastal lagoon in China. Previous studies suggested that the tide type in the lake belongs to irregular diurnal tide within the hybrid tides. In this paper, the authors calculate the tide coefficient 1.1 and suggest that it belongs to irregular semidiurnal tide based on their measurements and calculations. Analysis of the Pinqing Lake's sedimenta-tion environment is a typical example to study the evolution of lagoons in the coastal area. The hydrodynamics, transportation of various sediments and the chronological study of the sedimentations are presented in this paper. Combining the under-standing of the geological background, evolution processes and geomorphologic features of lagoon systems, particle compo-nents of 47 surface sediment samples from the Pinqing Lake are obtained and analyzed. The sediment types, grain size com-ponents, sediment sources and distributions, sedimentary environments and zonation of the Pinqing Lake are fully investigated. Analysis results suggest that sediments from the Pingqing Lake are mainly composed of clay, silt, sand, and gravels. A total of seven types of sediments are identified, including clayey silt, sandy silt, silty sand, gravel sand, sandy gravel, sand-silt-clay, and sand. The main type of the sediment in the Pinging Lake is clayey silt. The sediment is from different sources, and is con-trolled by different driving mechanisms. The results suggest there are four different sources with typical lagoon sedimentation. The Pinqing Lake is divided into six different zones according to sedimentary features, and different sedimentary regions in-dicate different sediment origins and dynamic environments.