Herein, a method of physical modeling of CO₂-brine-rock interaction and characterization of mineral and pore evolution at in-situ conditions is established. The nested preparation and installation of the same sample with different sizes could protect and keep the integrality of the millimeter-size sample in conventional high-temperature and high-pressure reactors. This paper establishes a procedure to obtain the three-dimensional comparison of minerals and pores before and after the reaction at in-situ conditions. The resolution is updated from 5-10 $\mu$m to 10 nm, which could be helpful for modeling CO₂-brine-rock interaction in unconventional tight reservoirs. This method could be applied to CO₂-enhanced oil recovery as well as CO₂ capture, utilization, and storage scientific research. Furthermore, it may shed light on the carbon sequestration schemes in the Chinese petroleum industry.