The interaction mechanism between CO₂ miscible fracturing fluid and reservoir core was clarified through the experiment of the change law of core pore structure，core mineral composition and permeability before and after the interaction of non flowback acid，CO₂ + solubilizer（or swelling agent or viscosity reducer）in CO₂ miscible fracturing fluid system with the core of Liuzan fault block under formation pressure and formation temperature by using the experimental methods such as core displacement，SEM，XRD and CT. The results showed that non flowback acid and the carbonic acid solution formed by the mixing of CO₂ and different water-soluble additives could dissolve feldspar and clay minerals and preferentially dissolve feldspar to produce minerals such as kaolinite and quartz. The dissolution effect of non flowback acid was the strongest，followed by the mixture of CO₂ and solubilizer and the mixture of CO₂ and viscosity reducer. The liquid permeability and gas permeability showed the same increasing trend，and the increasing range of liquid permeability showed a strong power relationship with the change of gas permeability before and after CO₂ miscible fracturing fluid injection. The research results provided some technical support for CO₂ miscible fracturing EOR technology.