Abstract: In order to quantitatively explore the correlation between saturation level and pore structure in sandy soils, we utilized 6 μm industrial micro-CT scanning to scan remolded samples of Nanjing silty fine sand during the dehumidification process. We extracted representative elementary volumes from various height positions of the three-dimensionally reconstructed samples and obtained the pore network models of these representative elementary volumes by utilizing the maximum ball algorithm. We calculated pore morphology and structural parameters and analyzed the evolution of pore structure during dehumidification stages. We actively analyzed the data and discovered that the predominant geometric shape of individual pores in the samples is elongated ellipsoids. During the dehumidification process, we observed minimal variations in the length of pore throats and their sphericity, while pore throat radius decreased. The orientation of pores in the samples exhibited cyclic changes: at a moisture content of 30%,the samples showed no predominant orientation; as the moisture content decreased from 20% to 5%,the mathematical expectation of pore plane angles and spatial angles both aligned towards 120°; whereas in dried samples, pores lost their predominant orientation again. By conducting a quantitative analysis of pore structure parameters, we determined that the continuous desaturation process of saturated samples of Nanjing silty fine sand could be divided into four distinct stages: from supersaturation to a moisture content of 30%,pore structure parameters increased, and pore connectivity improved; from a moisture content of 30% to 20%,pore structure parameters decreased, and pore connectivity decreased; from a moisture content of 20% to 5%,the samples desiccated and cracked, resulting in an increase in pore structure parameters and pore connectivity; from a moisture content of 5% to 0%,the crack structure was destroyed and filled with sand particles, leading to a decrease in pore structure parameters and pore connectivity. The research findings lay the groundwork for further understanding the liquefaction characteristics of unsaturated Nanjing silty fine sand.