Abstract: The grain size characteristics of sediments are very important for the analysis of wetland sedimentary environments and sediment transport trend. Based on the sediment samples of the Nanji wetland of Poyang Lake, this paper analyzes the composition, sedimentary type, dynamic environment and transport trend in the Nanji wetland using particle size analysis, Shepard triangle, C-M map, end member analysis and GSTA model. The results show that the sediments in the Nanji wetland are mainly fine silt, with an average percentage of 55.35%. The average particle size of the sediment is 5.24Φ, and the spatial distribution has a tendency of decrease from the southwest to the northeast. The types of sediments are mainly silt, clay silt, sandy silt and silty sand, of which silt accounts for 62.5%. The results of end member analysis show that EM1 and EM2 may be related to sediment transport caused by the lake current of Poyang Lake itself, EM3 indicates the source of sediment in Nanji wetland, and EM4 may be related to hydrodynamic changes of local environment. The pattern of the transport trend is most prominently from the east to the west and from the north to the south. The Nanji wetland formed by the complex interaction between the Ganjiang River and the Poyang Lake.