[Objective] The usefulness of watershed ecological compensation standards for obtaining the value of ecological products was studied in order to provide theoretical support for effective construction of ecological watershed environments. [Methods] The study was conducted at the Nandu River basin in Hainan Province. The InVEST model and ArcGIS were combined to assess the major ecosystem services within the Nandu River basin based on the concepts of ecological damage compensation and ecological protection compensation. The ecological compensation standard was calculated from the perspective of changes in ecosystem services. [Results] ① Between 2015 and 2020, there was clear spatial heterogeneity in ecosystem services within the Nandu River basin, with higher capacity for water conservation services, sediment retention services, and water purification services in the middle and upper reaches of the Nandu River basin, and lower capacity in the lower reaches of the basin. ② Between 2015 and 2020, the value of water conservation services in the watershed ranged from 2.05×10¹⁰ yuan to 2.61×10¹⁰ yuan; the value of sediment retention services ranged from 1.91×10⁹ yuan to 20.39×10⁸ yuan; and the value of water purification services ranged from 3.78×10⁷ yuan to 3.23×10⁷ yuan. The value of the volume of change in water conservation services ranged from 1.15×10⁹ yuan to 2.73×10⁹ yuan; the value of the volume of change in sediment retention services ranged from 1.34×10⁷ yuan to 1.04×10⁸ yuan; and the value of the volume of change in water purification services ranged from 7.99×10⁴ yuan to 4.01×10⁶ yuan. ③ Based on the values of the three service functions, the ecological compensation standard for the Nandu River basin was 9.06×10⁹ yuan, and the annual ecological compensation standard ranged from 1.18×10⁹ yuan to 2.82×10¹⁰ yuan. [Conclusion] During 2015—2020, the value of ecosystem services in the Nandu River basin ranged from 2.25×10¹⁰ yuan to 2.82×10¹⁰ yuan. Between 2016 and 2020, the ecological compensation rate at the Nandu River basin ranged from 1.18×10⁹ yuan to 2.84×10⁹ yuan. The upper and middle reaches of the Nandu River basin were the core areas providing integrated ecosystem services.