[Objective] This study aims to objectively quantify the thickness of soil physical crusts，clarify the development process， and characterize the pore structure of physical crusts in Quaternary red clay （QRC）. [Methods] Artificial rainfall simulation experiments were conducted to obtain soil physical crust samples under varying rainfall durations. The crust thickness was quantified using X-ray computed tomography（CT）scanning and a soil porosity threshold method，serving as a key indicator for analyzing physical crust development and revealing the formation process of QRC crusts. Furthermore，the structural characteristics of crusted soil samples at different developmental stages were investigated by extracting two-dimensional（2D）and three-dimensional（3D）pore indicators. [Results] 1）The development of physical crusts in QRC exhibited four stages：the initial phase of particle dispersion and soil pore-filling，the second phase of soil compaction induced by raindrops，the third phase of stabilization，and the final phase of erosion. The average thickness of physical crusts in QRC measured at rainfall durations of 1，10，30，60，90，and 120 minutes was 7.75，8.07，10.83，11.53，11.49，and 6.35 mm，respectively. Except for the final measurement， crust thickness showed an initial increase followed by stabilization. The development process（1~90 min）was represented by a cubic polynomial equation：y=10.17－4.69x+2.49x²－0.30x³ （R²=0.882 3）. 2）The QRC physical crusts exhibited distinct 2D and 3D structural characteristics across different developmental stages. In the mid-development stage，2D parameters generally showed decreasing trends in pore number，porosity，and equivalent pore diameter，while circularity progressively increased. For 3D parameters，the fractal dimension initially expanded before stabilizing，whereas pore surface area and connectivity density first increased，then decreased. All measured parameters exhibited significant variations across different crust development stages. 3） The combined approach of X-ray CT scanning and porosity threshold analysis enabled objective quantification of physical crust thickness. The development process of physical crusts was clarified through analyzing thickness variations and pore structural characteristics. [Conclusion] The findings establish a scientific foundation for studying hydrological processes and enhancing erosion modeling accuracy in severely compacted regions.