The ecological environment of the Shiyang River Basin is degraded, and the function of the ecological barrier is weakened. Therefore, it is of great significance to improve the ecosystem services and functions in this area. The growth of vegetation is an important factor that affects the supply of ecosystem services. It is necessary to quantitatively analyze the relationship between vegetation and ecosystem services. In this paper, the constraints of vegetation on water yield, soil conservation, and carbon sequestration in the Shiyang River Basin are analyzed by the constraint line method. At the same time, the spatial distribution of the three ecosystem service potentials in 2015 and the distribution pattern of the comprehensive potentials in the Shiyang River Basin were calculated. The results show that: (1) the constraint line between vegetation coverage and water production and soil conservation is a downward open parabola. That is, with an increase of vegetation coverage, the restraint effect gradually decreases and then gradually increases. The carbon service is positively convex. (2) Restrictive effects of vegetation coverage on water yield, soil conservation and carbon sequestration is temporally and spatially heterogeneous. (3) The characteristic of upgrading potentials of the three services is that the value of southwest is higher than of northeast with Coexistence of High Service Value and High Potential Value in the Shiyang River Basin. The Dongda, Xida, Xiying, and Gulang Rivers are the main contributors to the improvement of ecological services and service potential.