Abstract: As the main primary producer in freshwater lake ecosystem, submerged macrophytes organically connect lake water bodies and sediments, playing an important role in maintaining the health of these ecosystems. In order to understand the current degradation and causes of submerged macrophytes in Caohai Lake, Guizhou, we investigated the macrophyte community and sediment physiochemical properties. The spatial and temporal distribution patterns of submerged macrophytes and sediment nutrient characteristics were estimated using grid point and belt transect methods, and key factors impacting submerged macrophytes were identified. In addition, seed bank germination experiments were conducted to estimate the restoration potentia of submerged macrophytes in Caohai. Results showed the presence of 10 submerged macrophyte species: Charophyte sp., Myriophyllum spicatum, Stuckenia pectinata, Najas marina, Potamogeton lucens, Hydrilla verticillate, Potamogeton perfoliatus, Ceratophyllum demersum, Potamogeton maackianus, Polygonum amphibium, and Potamogeton acutifolius. The coverage and biomass of these macrophytes exhibited significant seasonal and spatial variations. A significant negative correlation between the total coverage of submerged macrophytes and nutrient salts in the water and sediment indicated that these plants play an ecological role in reducing nutrient levels, while excessive nutrients negatively affect the growth. At present, nutrient release from sediments in Caohai appears to be the main factor affecting submerged macrophyte growth. Compared to other lakes, surface sediment of Caohai is characterized by loosen and high moisture content, making it difficult for macrophytes to plant and germinate. Meanwhile, the loosen sediment also easily releases soluble nutrients into the water. Furthermore, the photosynthesis of submerged macrophytes is impacted by reduced water transparency caused by excessive phytoplankton growth and shading from suspended plant residues. Despite these challenges, Caohai has good potential for the natural restoration of submerged macrophytes. However, the current high nutrient concentrations and the loose nature of the sediment limit this restoration. This study provides a theoretical basis and technical reference for future implementation of stable-state transformation control, water quality improvement, and aquatic plant restoration strategies in Caohai.