In order to investigate the impact on the evolution of the full-pore structure of coal under CO2 phase change impact fracturing , this study investigates the mechanism and influence of CO2 phase transition impact fracturing using coal samples subjected to CO2 fracturing and pristine structural coal samples from the same locations were selected from Dayun Coal Mine and Dahebian Coal Mine in Liupanshui, Guizhou Province, and the pore characteristics and fractal properties of the coal body before and after fracturing were analyzed by mercury intrusion porosimetry (MIP), low-temperature N2 adsorption test, and low-pressure CO2 adsorption test. and Combine the Merger, FHH, and Sierpinski models. The study shows that the pore structure of the original coal samples is mainly composed of slit pores formed by the accumulation of flake-shaped particles, and after the CO2 phase change shock fracturing treatment, a large number of ink bottle-shaped semi-open/open pores are generated in the coal sample, leading to further development of the pore structure. In the process, micropores develop into medium pores, medium pores develop into large pores, and large pores develop into larger pores, In other words, after CO2 fracturing, the number of micropores in the coal decreases, while the number of mesopores and macropores increases. Further analysis of the fractal properties showed that CO2 phase change impact fracturing exerted differential effects on the pore structures of micro-, meso-, and macropores within the coal body. For micropores, the fractal dimension increases, indicating that the pore structure becomes more complex and the non-homogeneity is enhanced. In contrast, for macropores, the fractal dimension decreases, suggesting that the pore structure becomes simpler and the non-homogeneity is weakened. For mesopores, in the low-pressure region (P/P0 ≥ 0.5), the fractal dimension also decreases, indicating that the pore structure simplifies, the pore surface becomes smoother and flatter, and the non-homogeneity was further weakened. However, in the high-pressure region (P/P0 < 0.5), there was no obvious pattern in the fractal dimension changes of the coal samples before and after CO2 fracturing. The results of engineering applications show that CO2 phase change shock fracturing technology can significantly reduce the gas flow attenuation coefficient and increase the permeability coefficient of coal seams, which can effectively improve the permeability of coal seams, reduce the gas content of coal seams, and improve the efficiency of gas extraction. This not only helps to improve the safety of coal mine production and reduce the risk of safety accidents such as gas outbursts, but also provides a strong guarantee for the efficient production of coal mines.