Abstract: [Objective] The construction of the changing slope cropland to terrace project plays a crucial role in preserving cropland resources, reducing soil erosion, and promoting grain production. In the process of selecting sites and constructing terrace projects, balancing the benefits of soil and water conservation with economic returns is key to achieving a win-win situation for both soil conservation and food security. [Methods] Using remote sensing and spatial analysis techniques, the spatial distribution of terraces in Danjiangkou City was identified, and small watersheds were delineated. By combining the Chinese Soil Loss Equation (CSLE) model with field investigations, the tradeoff between soil and water conservation benefits and crop value-added in the changing slope cropland to terrace project was evaluated. A linear optimization method was employed to search for the optimal spatial layout of the project under multiple scenarios. [Results] The terraces and slope cropland in Danjiangkou City are mainly distributed in the central and northern watersheds, where they exhibit higher total benefits in terms of soil and water conservation and crop value-added economic benefits. The results of the spatial optimization analysis for each small watershed indicate that under the soil and water conservation priority scenario, the changing slope cropland to terrace project is primarily concentrated in the southwestern watershed, whereas under the crop value-added economic benefits priority scenario, the project is more concentrated in the central watershed. The linear optimization results under multiple scenarios show a significant tradeoff between the soil and water conservation priority and the crop value-added economic benefits priority: in the scenarios, the maximum soil and water conservation benefit is a reduction of approximately 3.207 million tons of erosion, with crop value-added economic benefits of around 1.7811 billion yuan. Conversely, the maximum crop value-added economic benefit is about 1.8745 billion yuan, with soil and water conservation benefits reduced to approximately 3.013 million tons. The Pareto optimal solutions reflect the tradeoff between the two. [Conclusion] This study quantifies the tradeoff between soil and water conservation and crop value-added economic benefits in the changing slope cropland to terrace project through spatial optimization methods and provides a series of Pareto solutions for decision-makers. The research results offer valuable insights for high-standard cropland development and integrated small watershed management in China.