[Objective] Objectively quantify the physical crust development process and explict the development process and structure characteristics of physical crust of Quaternary red clay (QRC). [Methods] The study utilized an artificial rainfall simulation experiment to obtain soil crust samples under different rainfall duration. CT scanning and the threshold of soil porosity were employed to quantify the thickness of crust, which served as an indicator of the process of physical crust information and reveal the development process of QRC. Additionally, we examined the structural properties of soil samples with varying degrees of crust development by extracting two-dimensional (2D) and three-dimensional (3D) pore indicators from the soil crust samples. [Results] (1) The formation of QRC’s physical crust can be divided into separate phases. These stages can be summarized as follows: the initial stage involves particles spreading out to occupy the empty spaces in the soil; the second stage involves droplets coming together and becoming more compact; the third stage is when the soil becomes stable; and the fourth stage is when erosion takes place. The average thickness of the physical crusts in the QRC increased with time during rainfall, with values of 7.75, 8.07, 10.83, 11.53, 11.49, and 6.35 mm at 1, 10, 30, 60, 90, and 120 minutes, respectively. Except for the final result, the developing process (1-90 min) can be represented by the one-dimensional cubie equation y=10.17-4.69x+2.49x2-0.30x3 fitted (R2=0.8823). (2) The QRC physical crusts exhibited distinct 2D and 3D structural features at various phases of development. In the mid-development stage, the 2D indicators often show a steady decrease in pore number, porosity and equivalent of diameter, along with a gradual increase in circularity. The 3D indicators exhibited a pattern of the fractal dimension initially expanding and the stabilizing. In contrast, the pore surface area and connectivity of density showed an initial increase followed by a decrease. Each measure exhibits varying degrees of substantial disparities during different phases of crustal evolution. (3) "X-ray computed tomography and porosity threshold" can objectively quantify the thickness of physical crust, and indicate the development process of physical crust according to the change of crust thickness and pore structure characteristics. [Conclusion] The results provide a basis for investigating hydrological phenomena and precisely modeling erosion in regions afflicted by significant soil compaction.