Abstract: In order to study the influencing factors for the enrichment of organic matter in Mesozoic and Cenozoic shale in lacustrine basins, the Pearson analyses of algal assemblages, physical and chemical properties of water body, sedimentary grain size, magnetic susceptibility and chromaticity were carried out from the aspect of modern lacustrine deposition. The coupled relationship between modern algal assemblages and water body, surface sediments in the Zhongnei Lake, which is a semi-enclosed shallow lake in the Songnen Plain, showed that topography and wind field affected the enrichment of organic matter in semi-enclosed brackish lakes with acidic and mixed water bodies. In different sites of the Zhongnei Lake, the abundance of cyanobacteria, green algae and diatoms are affected by water temperature and has a certain relationship with the degree of sediment sorting. Water temperature and sediment sorting are significantly controlled by the interference of local wind field.