Abstract: The soil water retention curve (WRC) is crucial in hydrological and agricultural characteristics, closely linked to pore distribution and soil structure. The development of loess caves in the western region of Shanxi is significant, leading to substantial soil erosion and the destruction of arable land. The distribution of these loess caves is closely related to the hydraulic properties of the soil, and WRC studies provide both direct and indirect insights into these properties. To determine the hydraulic resources and their evolution in loess at different depths and areas within this region, we utilized CT technology and 3D image analysis programs. The pore size distribution of loess samples was obtained through a series of image processing methods. The Young-Laplace equation was used to estimate soil water retention by calculating the amount of water released from the samples under varying degrees of matric suction. The van Genuchten (VG) model was then employed to fit the resulting WRC curves. Since the water content in porous media cannot fall below the residual water content of the substrate, evaporation tests were conducted to determine an average residual saturation of 0.123, allowing for the estimation of an actual drainage pore occupancy of 88%. The results showed that the porosity obtained from image analysis was approximately 12% smaller than that measured physically, primarily due to the limitations of the CT scan sample size. To reduce calculation errors, a corresponding correction factor was applied to adjust the pore sizes, which mainly ranged between 1.04 and 1.06. Pores larger than 20 μm in loess follow a log-normal distribution, accounting for over 70% of the total pore volume, and they are the primary spaces for water retention and release. In samples from different depths, the pore structure undergoes significant changes as depth increases from 2 m to 8 m. Due to compaction effects, the average pore size decreases by 7.31%, and the size distribution becomes broader. This leads to a 45.55% increase in the air entry value, a smoother WRC curve, and an increase in both sphericity and aspect ratio, resulting in reduced permeability. Consequently, deeper soil layers demonstrate better water retention characteristics. Across the entire region, porosity slightly decreases from north to south, which is closely related to the decrease in loess particle size. The clay content increases by 163.82%, causing the average pore size to shrink by 18.13%, and the air entry value to rise by 267.24%. The increase in pore sphericity and decrease in aspect ratio further enhance the soil's water retention capacity. In this region, most loess caves have diameters ranging from 0.5 to 1.5 meters and depths between 4 and 8 meters. The vertical variation in the WRC of the loess layers, the presence of slope critical interfaces, and the widespread development of primary seepage channels such as vertical joints and unloading cracks provide the material and spatial foundation for the formation of loess cave erosion. These caves are formed under the combined effects of hydraulic erosion and gravitational deposition. The highly permeable loess layer in the northern part inhibits the formation of caves, while the low permeability soil in the southern part promotes surface runoff, increasing and then a decrease in cave density from north to south. In summary, μCT provides a relatively simple and rapid method for characterizing key features of soil hydrology and agricultural properties. The formation of loess caves depends on various factors such as hydraulic characteristics and geographical location, while the trends in WRC variations offer important insights into the development patterns of cave depth and density.