The microstructure of soil is an internal cause that affects its deformation, failure, strength, and other characteristics. In order to explore the characteristics of pore distribution in the soil, mercury intrusion tests and nitrogen adsorption tests were performed on the original and remodeled samples of Liuzhou red clay. Aggregates of various sizes are developed in red clay. Due to the cementation of free iron oxide, the interior of the granules has high stability, and will not be damaged under general loading or disturbance. There are a large number of small-sized pores inside the granules. Together with the pores between the grains, the pore space of the red clay is formed; the bimodal structure of the pore size distribution in the red clay is very obvious, and the pores in the grains remain stable due to strong cementation. The pores in the soil mass formed by different sample preparation methods are stable. Compared with the original soil sample, the remolded soil sample has a larger pore volume and a loose structure. The pore measurement of the mercury pressure test is comprehensive and covers a wide range, including large pores and Micropores, overall pore distribution and pore cumulative volume are clearly displayed. The nitrogen adsorption test focuses more on the measurement of micropore volume, and the measurement accuracy is high, so the combination of the two can be more detailed and accurate.