Clarifying the complex relationships among ecosystem services (ESs) and the driving mechanisms of ecosystem service (ES) is essential for supporting regional ES and ecological sustainability. Although studies on ES relationships provide guidance for regional ecological management, the driving mechanisms of ES have not been adequately studied, especially in areas with complex natural environments and progressive urbanization. Combined with the data on land use, climate, NDVI, and soil data, this paper aims to explore this issue by analyzing the relationships among ESs and the driving mechanisms of ESs in the western Sichuan Plateau region of China. Firstly, the temporal and spatial distribution characteristics of five ecosystem services (food supply, water supply, habitat quality, soil conservation, and carbon storage) from 2000 to 2020 were analyzed by the InVEST model. Second, the trade-offs/synergistic relationships among ESs were analyzed using SPSS as well as the Pearson product-moment correlation coefficient method in MATLAB. Finally, the Geodetector model was further used to reveal the influencing factors of ecosystem services in the western Sichuan Plateau. The results showed that: (1) Water supply decreased in the western Sichuan Plateau from 2000 to 2020, but increased in the eastern part; habitat quality was generally good in the whole Sichuan Plateau, but decreased in some areas; carbon storage showed an overall improving trend; soil conservation showed an overall increasing and then decreasing trend, and food supply services showed an increasing trend. (2) From 2000 to 2020, food supply and other services in the western Sichuan Plateau were in a trade-off relationship; all other service pairs showed a synergistic relationship. (3) In terms of space, the relationships between ecosystem services showed spatial heterogeneity. There was a synergistic relationship between food supply and habitat quality in some areas, such as Litang County and Xinlong County, and there was a trade-off relationship between water supply and carbon storage services in some areas, such as Ruoergai County and Daocheng County, etc. (4) The Geodetector results showed that food supply and soil conservation were mainly influenced by the slope (0.682, 0.672), annual precipitation was the strongest explanation for water supply (0.967), and habitat quality and carbon storage were the most influenced by NDVI (0.876, 0.828); meanwhile, each ecosystem service was interactively influenced by multiple factors. Based on the results, we proposed ecological management recommendations for the western Sichuan Plateau, the most important one being that the western Sichuan Plateau should protect and rationally use the existing natural resources, especially the existing forest and grassland resources, and at the same time reform the agricultural structure and scientifically plan urban development, to promote the coexistence of cities and nature. We took the western Sichuan Plateau of China, where urbanization and a complex natural environment are in opposition, as an example, to explore its ecosystem services, relationships, and driving mechanisms, and then put forward suggestions on ecological management and control, providing a reference for future regional coordination between urbanization and the natural environment. © 2022 by the authors.