Looking at the research on desertification worldwide, numerous studies have examined the current status and consequences of desertification from a macro perspective. However, little is known regarding the inherent processes of desertification, as well as the ecological role of shrubs in preventing grasslands desertification in arid regions. We hypothesized that in arid areas, the presence of shrubs increased soil nutrient levels and soil water retention capacity, facilitated understory plants and soil biotas, which in turn reduced wind erosion and increased soil consolidation. These interconnected ecological processes jointly prevented the movement of sand material and arid grasslands from changing into deserts. In order to test the hypothesis, we took the desertification grassland in the Alashan area of the Inner Mongolia as a sample site to study sand fixation ability, improving soil water retention capacity, ameliorating soil nutrition and facilitating biota community of Caragana shrubs, and explore the role of Caragana shrubs in preventing grasslands desertification in arid regions from the perspective of organism, soil, water, and sand material movement. Our aim was to understand the ecological processes by shrubs preventing arid grasslands from changing into deserts. In the desertification grassland of Alashan region, the cover of Caragana shrubs was about 12.40%. On the 100 m² land, the soil-fixation by existing shrubs was 2.01 m³, soil-fixation efficiency was 167 cm³/g shrubs fresh weight, and the annual growth of the Caragana shrubs on 100 m² land could increase the soil-fixation capacity by 0.264 m³. Caragana shrubs increased both soil water content (shrub effect SE=0.120) and rainwater retention (SE 0.155), improved soil nutrition (soil organic matter SE 0.234, available nitrogen SE 0.338, available phosphorus SE 0.256, and available potassium SE 0.089), facilitated plant communities (species richness, abundance, height, and biomass; SE 0.298) and soil biota communities (richness and abundance of soil microorganisms and soil nematodes; SE 0.302), increased soil enzyme activities (alkaline phosphatase, sucrase, urease, and catalase; SE 0.191-0.365). In conclusion, our research suggested that Caragana shrubs prevented grasslands from changing into deserts through multiple interrelated ecological processes, such as increasing water retention (path coefficient PC 0.43), accelerating fertilization (PC 0.39), facilitating plant (PC 0.34) and soil microbial community (PC 0.20), and their combined effects on soil fixation. Each of the five Caragana species had its own advantages and disadvantages in different aspects of preventing desertification. This would be one of the reasons why these species can coexist in desert areas. Caragana shrubs, as the main vegetation in extreme arid regions, play an important role in preventing grasslands desertification in Alashan arid region.