Abstract: Acting as the main primary producer of freshwater lake water ecosystem, submerged macrophytes organically connect lake water bodies and sediments, and play an important role in maintaining the health of lake water ecosystems. In order to understand the current degradation situation and reasons of submerged macrophytes in Caohai in Guizhou, this study investigated submerged macrophyte community and sediment physiochemical properties, and estimated the currently spatial and temporal distribution patterns of submerged macrophytes and sediment nutrient characteristics using grid point method and belt transect method, and determine the key factors that impact submerged macrophytes. In addition, Seed bank germination experiments of Caohai were conducted to estimate restoration potentiality of submerged macrophyte. Results showed that a totally current 10species of submerged macrophytes including Charophyte sp, Myriophyllum spicatum, Stuckenia pectinata, Najas marina, Potamogeton lucens, Hydrilla verticillate, Potamogeton perfoliatus, Ceratophyllum demersum, Potamogeton maackianus, Polygonum amphibium and Potamogeton acutifolius were found in Caohai. The coverage and biomass of submerged macrophyte in Caohai showed obviously seasonal and spatial variations. The significant negative correlation between the total coverage of submerged macrophytes and nutrient in water and sediment indicated that submerged macrophytes have the ecological function of reducing nutrient in lake restoration, and excessive nutrients might have negative effects on the growth of submerged macrophytes. At present, the release of nutrient from sediments in Caohai could be the main factor affecting the growth of submerged macrophytes. Compared to other lakes, surface sediment in Caohai is characterized by loosen and high moisture content, which result in submerged macrophytes are difficult to plant and germination. Meanwhile, the loosen sediment is easy to release soluble nutrient into waterbody. Photosynthesis of submerged macrophytes have been impact by water transparency decline originated from phytoplankton excessive propagation and shading of suspended plant residues. Caohai has a good potential for natural restoration of submerged macrophytes, but the higher nutrient concentration and the loosen property of sediment currently limited submerged macrophytes restoration. The study could provide theoretical basis and technical reference for the subsequent implementation of Caohai steady-state transformation control, water quality improvement and aquatic plant restoration technical scheme.