Abstract: The comprehensive analysis of grain size can effectively reflect changes of sedimentary environments and sediment transportation trends, which is a crucial aspect in marine sedimentation investigation. In this study, 108 surface sediment samples were selected from the sea areas surrounding Weihai for grain size components and parameter analyses, and grain size trend analysis. Results reveal that the sediments are composed by sandy silt and silt on average grain size of 3.14Φ –5.87Φ and sorting coefficient of 1.57Φ–2.91Φ. Most samples exhibit nearly symmetrical skewness and sharp kurtosis characteristics. By comparing the features of the grain size parameters and frequency curves, the study area was divided into four distinct sedimentary zones (Zone Ⅰ - Zone Ⅳ) based on previous studies on prevenance. Zone Ⅰ is predominately composed of Yellow River sediments influenced by tidal currents. Zone Ⅱ is characterized by combination of Yellow River materials and fine nearshore sediments. Zone Ⅲ is primarily influenced by wave-dominated near-source sediments and fine sediments from the Yellow River. Zone Ⅳ consists mainly of coarse detrital sediments. Furthermore, simulation in the Gao-Collin model reveals three distinct trends in net sediment transport around Weihai: offshore transport, onshore transport, and alongshore transport, which is consistent with the distribution of sand, silt, and clay components. Two convergence centers were recognized: the first one exhibits an offshore trend of counterclockwise transport in the northwestern area and near Liugong Island, and the second one shows a net transport towards the shore, and the transport trend changes from SW to SE. The two centers merged in the northern area between Gushan and Boyu, forming a convergence zone of fine particles. This study provided fundamental geological insights to support marine area planning and sustainable development of the environment.