[Objective] To explore the intrinsic mechanism of ecosystem service value (ESV) evolution, an optimal allocation model for ecological agriculture with towns and river basins as units was investigated.[Methods] Based on the theories and methods of land use and ecological service value, with the Shima River basin land use data from 2010 to 2020, the Clue-S model was used to simulate the land use pattern in 2025, and the results of land use spatial distribution and optimal allocation under three scenarios of ecological security, farmland priority and construction and development in 2025 were obtained, and the space-time pattern of watershed ESV under each scenario was analyzed.[Results] From 2010 to 2020, the ecological service value of the Dongguan section of the Shima River basin decreased by 1.80×10⁷ yuan, which was mainly converted into cultivated land, forest and orchard. The ESVs were 9.44×10⁷, 9.62×10⁷, and 9.38×10⁷ yuan under the condition of giving priority to the ecological security of the construction and development of cultivated land in 2025. In addition to ecological security, the other two scenarios showed a decline from the ESV in 2020.[Conclusion] In areas with rapid urbanization and a prominent contradiction between ecology and development, the simulation and analysis of watershed ESV is helpful to enhance the understanding of the spatial distribution of ESVs under different development modes and to provide macroscopic reference for land use planning and coordinated development of an ecological economy.