Abstract: Ecosystem services and eco-environmental sensitivity assessments can reveal the quality of regional ecosystems and the supply capacity of ecological products and provide a scientific basis for constructing ecological security patterns. This study selected the Ningxia Hui Autonomous Region and systematically evaluated the ecosystem services, including windbreak and sand fixation, water conservation, soil and water conservation, biodiversity maintenance, and sensitivities such as soil erosion and land desertification. The minimum cumulative resistance (MCR) model is used to identify ecological sources, construct ecologically resistant ecosystems and define ecological security buffer zones, identify ecological corridors and key ecological nodes, and develop an ecological security pattern in the region. The results show that: (1) the area of important ecosystem services is 14,280.05 km², primarily distributed in the Helan Mountains in the northwest, Habahe in the east, Luoshan in the middle, and Liupanshan in the south. The sensitive area of the ecosystem is 7 340.58 km², primarily distributed in the soil erosion control and desertification control areas in the southern Ningxia and Shapotou districts, respectively; (2) When the evaluation results were combined with the spatial distribution of nature reserves, the ecological source area of the whole region was determined to be 16,300 km², including Helan Mountain, Liupan Mountain, Haba River Nature Reserve, a section along the Yellow River, and the southern mountains. The ecological security buffer zone accounted for 67.93%, 22.92%, and 9.15% of the country's land area according to high, medium, and low levels, respectively; (3) There are 64 ecological corridors and 12 ecological nodes, all of which are dense in the middle and sparse in the north and south, which is consistent with the distribution of ecological sources and their degree of fragmentation. The research shows the ecological sources in the mountainous areas of Ningxia and the ecological corridors and nodes in central Ningxia are key areas to ensure ecological security, and ecological protection and restoration should be further strengthened.