Abstract: The paper aims to study the influence of submerged plants Vallisneria natans and Hydrilla verticillata on water environment, Vallisneria natans and Hydrilla verticillata were planted alone and mixed under the restrained conditions. The authors comparatively studied the concentration difference of total nitrogen (TN), total phosphorus (TP), ammonium nitrogen (NH₄ -N), chlorophyll-a, total suspended mass (TSS) and total organic nitrogen (TOC) in the water of Vallisneria natans alone, Hydrilla verticillata alone and mixed of the two. The results showed that: the influence of Vallisneria natans and Hydrilla verticillata on water environment was different. When Vallisneria natans was planted alone, the content of total nitrogen (TN) and ammonium nitrogen (NH₄ -N) in overlying water was higher than the other two processing methods, but the content of total phosphorus (TP) and chlorophyll-a, TSS and TOC were lower than that of Hydrilla verticillata planted alone and the mixed planting of the two. The results also showed that Vallisneria natans which could reduce the content of total phosphorus and chlorophyll-a in overlying water was better than Hydrilla verticillata, it had a good effect on maintaining water quality.