Abstract: Ecosystem services are the bridge between ecology and human well-being, hence rapid and accurate assessment of their changes is very important for regional sustainable development. Sustainable Development Goal 15 (SDG15) also provides a new direction for the calculation of ecosystem services. The Qianjiangyuan is the origin of the Qiantang River and the only pilot national park in the Yangtze River Delta region at present. However, it is necessary to further clarify the spatiotemporal distribution and changes of the ecosystem services in Qianjiangyuan. Based on the 2010—2020 remote sensing monitoring data of land cover in the pilot area and oriented to the SDG15 indicators, this study quantitatively assessed the spatiotemporal variation characteristics of ecosystem services in Qianjiangyuan National Park using the InVEST model and the univariate and bivariate Moran’s I spatial autocorrelation methods. The results are shown as follows. ① From 2010 to 2020, the values of ecosystem services gradually increased by 15.21%. Specifically, cultural services grew the fastest by 19.70%, regulating services grew by 16.27%, and supply services decreased by 1.72%. ② The spatial distribution of ecosystem service values showed a gradually decreasing trend from the northeast and the southwest to the center. ③ The spatiotemporal changes in land cover types slowed the growth of ecosystem services under the land development restriction. The reduced areas of wetlands and water bodies and ecological quality led to declined spatial aggregation and value of some ecosystem services. ④ Ecosystem services can be regarded as an indicator of SDG15. The study results are expected to provide a theoretical basis and technical support for the construction of Qianjiangyuan National Park and support the sustainable development of the regional ecological environment.