Based on the water quality monitoring data of Lake Wuliangsuhai from 2011 to 2020, the comprehensive nutrition index method, PCA sorting method and ArcGIS Kriging interpolation method were combined to comprehensively evaluate the interannual temporal and spatial variation characteristics of the eutrophication degree of Lake Wuliangsuhai from 2011 to 2020. Additionally, this study aimed to elucidate the key drivers that contributed to changes in water eutrophication. The research results showed that: (1) The peaks of TP and TN of Lake Wuliangsuhai occurred during the flat water period, the peak of NH₃-N was observed during the dry season, and the peak of COD_Mn was during the wet season. The overall water quality was found to be mainly surface water. (2) Between 2011 and 2020, the water quality of the lake underwent a transition from mild eutrophication to moderate eutrophication, followed by a retum to mild eutrophication, and ultimately to a state of medium nutrient status. The proportion of the lake area with a comprehensive nutrient index of 60-70 (moderate eutrophication) decreased from 21.49% to a point where it has now nearly disappeared, while the proportion of the lake area with a comprehensive nutritional index of 30-50 (medium nutrition) increased from 23.84% to 44.87%. (3) The ecological water replenishment of Lake Wuliangsuhai was negatively correlated with TN, TP, COD_Mn and comprehensive nutrient status index, This indicates that ecological water replenishment was another key driver that impacted the trophication of lake water.