Abstract: Small watersheds are the fundamental units for ecological governance and agricultural development in mountainous regions, possessing an intact ecosystem structure and independent eco-economic functions. Integrating circular agriculture with soil and water erosion control at the small watershed scale can realize the coordinated advancement of ecological and economic benefits. Constrained by complex terrain and fragile ecological conditions, the circular agricultural systems in small watersheds of southern China mountainous areas are plagued by multiple bottlenecks, including incomplete planting-breeding circulation chains, insufficient quantitative evaluation of ecological effects, poor adaptability of core technologies, insufficient coordination of policies and mechanisms, and a shortage of interdisciplinary research. These constraints hinder the systematic integration and large-scale popularization of such systems. Based on circular economy theories and sustainable development goals, we analyzed the deve-lopment status of circular agricultural systems in small watersheds of southern China mountainous areas, covering four major dimensions: the integration of comprehensive soil and water erosion control with ecological agriculture, the combination of planting-breeding production and agricultural waste resource utilization, the construction of agroforestry compound systems, and the integrated development of characteristic industries and eco-tourism. We further analyzed the prevailing challenges, such as fragile eco-environments, imperfect technical and model standards, restrictions from capital investment and market mechanisms, as well as insufficient administrative coordination and professional talents. We then proposed corresponding optimization countermeasures from four dimensions: technological innovation, ecological conservation and restoration, industrial integration, and policy support plus organizational model innovation. This would provide a theoretical basis and practical references for constructing circular agricultural systems tailored to the characteristics of southern China mountainous areas and achieving harmonious development between agricultural exploitation and ecological protection.

Key words: circular agricultural system, small watershed, sustainable development, agricultural resource optimization, modernization