Lake Qionghai is one of 11 natural lakes in the Yunnan-Guizhou Plateau with an area of >25 km². Based on the monitoring data of the Lake and its inflow rivers, the water quality characteristics of the inflow rivers and the response of the lake were explored in this study. Results showed that the water quality of inflow rivers in Lake Qionghai was significantly heterogeneous in 2021, and the 11 rivers could be divided into three pollution types: natural, agricultural, and urban. Three natural rivers, including the Guanba River, had favorable water quality, while eight urban and agricultural rivers (R4-R11), including the Gaocang River, had poor water quality and excessive pollutant concentrations. During 2011-2020, the nutrient concentration of the main inflow rivers (Guanba, Ezhang, and Xiaoqing Rivers) decreased or increased first and then decreased, and water quality gradually improved. The land use change in the catchment was the main factor contributing to the spatial heterogeneity of the river water quality. It was also one of the reasons for the improvement in river water quality from 2011 to 2020. Moreover, there was a significant difference in the water environment and its response to river water quality in Lake Qionghai in 2017-2021 due to the lake's hydrological condition and river pollution types. Gaojianwan (L5) had shallow water and weak environmental capacity, hence its concentration of pollutants and chlorophyll-a was high, reaching a eutrophic state in 2021. Meanwhile, because of the deep water and strong environmental capacity, the pollutant concentration and trophic state index of the lake area of Guanba, Ezhang, and Xiaoqing Rivers (L1-L3) and Xiaoyucun (L4) were low. However, there were seasonal differences in the response between trophic level and river water quality due to the different pollution types of the inflow river. In addition, from the perspective of pollution control areas, the inflow rivers R4-R11 and lake area L5 should be the focus of water environment restoration in the Qionghai basin.