Abstract:The Yun-Gui-Chuan-Yu Ecological Security Barrier is situated in Southwest China, encompassing the provinces of Sichuan, Chongqing, Guizhou, and Yunnan. It serves as a vital water source conservation area and a core zone for biodiversity protection for the Yangtze, Yellow, and Pearl River basins, playing a crucial role in China’s national ecological security. Since the 18th National Congress of Communist Party of China, under the guidance of Xi Jinping’s Thought on Ecological Civilization, the region has made significant strides in water resource protection, soil erosion and mountain disaster control, biodiversity conservation, and ecosystem restoration, resulting in noticeable improvements in environmental quality and ecosystem services. However, the region still faces multiple challenges, including intensified non-point source pollution in the water environment under complex climate change, inadequate biodiversity protection mechanisms, the spread of rocky desertification, and increased risks of mountain disasters. To achieve the goals of regional ecological security and sustainable development, it is essential to strengthen scientific and technological support, enhance an integrated “sky-earth-space” monitoring system, delve deeply into the coupling mechanisms among water, soil, air, biology, and disasters, explore a holistic restoration model encompassing mountains, rivers, forests, farmland, lakes, grasslands, and mine ecosystems, improve the region’s green disaster reduction capabilities, promote the realization of ecological product value, and foster cross-regional collaboration, thereby promoting harmony between humans and nature and high-quality development. This study systematically analyzes the current status, issues, and challenges in the Yun-Gui-Chuan-Yu Ecological Security Barrier area concerning water resources, biodiversity, ecosystem protection and restoration, environmental pollution control, climate change response, rocky desertification control, and mountain disaster risk prevention and control. It also proposes targeted development directions and strategic recommendations.