Abstract: Background Exploring the ecological and environmental effects of land use transformation holds significant practical importance for promoting regional ecological environmental protection, optimizing land resource allocation, and achieving sustainable and efficient land use. However, in the Qinghai Lake Basin, research in this field still awaits further clarification and in-depth study. Methods This study has the Qinghai Lake Basin as the research area, and utilized land use/cover data from 1990， 1996，2002，2009，2015 and 2021(six periods in total). Using analytical methods such as the land use transition matrix, ecological environment quality index, and ecological contribution rate of land use transformation, this study quantitatively explored the characteristics of land use transformation in the Qinghai Lake Basin and its impact on the ecological environment. Results The results show that from 1990 to 2021, 1) there was a significant change in land use in the Qinghai Lake Basin, with the total area of water bodies increasing by 196.81 square kilometers, and slight growth in grasslands and wetlands; 2) The ecological environment quality index of the basin increased from 0.4729 in 1990 to 0.4774 in 2021, indicating an overall improvement in ecological quality. Among them, the areas of moderate and high ecological quality are progressively expanding, while the area of low ecological quality is diminishing; 3) The change of single land use type has only limited correlation to the overall change of ecological environment effect. Conclusions Although improvements and deteriorations in the ecological environment coexist, the overall trend of enhancement of surpasses that of degradation. The positive transformation of wasteland into grassland and water bodies has been a key driver in enhancing the ecological quality, significantly promoting a positive development of the ecosystem. The increase in grassland effectively stabilizes soil, reduces surface runoff, and thereby mitigates soil moisture, The restoration and conservation of wetlands and water bodies enhance water conservation capacity, increase soil moisture, provide habitats for biodiversity, and thereby contribute to increased biodiversity.