Abstract: Lake Baiyangdian is the largest shallow lake in North China, which is of great significance to the ecological security of Xiong'an New Area. Based on the survey data of submersed macrophyte communities and main environmental indexes in Lake Baiyangdian in 2010 and 2019, the spatial-temporal variations of the composition and distribution of submersed macrophyte communities and their relationships with water level and water quality were analyzed. The quality of submersed macrophyte community was evaluated using the Submersed Macrophyte Quality Index (SMQI), and water quality was evaluated using the comprehensive Water Pollution Index (WQI). Compared with the data in 2010, the species number of submersed macrophyte in the whole lake decreased from 10 to 9. The dominant species changed from Ceratophyllum demersum, Potamogeton pectinatus and Chara sp. to C. demersum, P. pectinatus, Utricularia vulgaris and Myriophyllum spicatum. There was no significant change in the frequency of C. demersum, but the frequency of P. pectinatus, U. vulgaris, M. spicatum and Najas marina increased significantly, while the frequency of Potamogeton malaianus and Hydrilla verticillata decreased. The quality of submersed macrophyte community improved in most sub-lakes, and the central and eastern lake areas were generally better than the western lake areas near the Fu River inlet, and the average value of SMQI increased from 3.87 to 4.98. The water quality was obviously improved in almost all sub-lakes, especially in the area from the inlets of Fu River and Xiaoyi River to the Lake Shaochedian in the north, and the average value of WQI decreased from 2.80 to 0.77. Redundancy analysis showed that the distribution of the submersed macrophyte communities was significantly correlated with the concentration of total phosphorus and chlorophyll-a, followed by water depth and transparency. The analysis of the relationship between submersed macrophytes and water depth/transparency showed that water supplement in winter and spring was not conducive to the germination and biomass growth of submersed macrophytes. In 2019, the water level of Lake Baiyangdian exceeded the suitable range for submersed macrophytes (water depth/transparency <3). Analysis of relationship between submersed macrophytes and water quality showed that there were no algal areas in Lake Baiyangdian, hence the water quality basis for natural restoration of submersed macrophytes was established. We suggest to take account of the photosynthetic characteristics and life history of submersed macrophytes when implementing the ecological water supplement, and to implement a balanced harvesting for sub-lakes with high submersed macrophytes biomass in Lake Baiyangdian.