The use of closed goafs to store CO2 is one of the important ways to capture, utilize and store carbon, and play an important role in helping to achieve the "dual carbon" goal. Aiming at the problem of identifying the main controlling factors of CO2 sequestration stability in closed coal mine goafs, the stability influencing factors are systematically selected from three aspects: hydrogeological conditions, goaf occurrence characteristics and cap conditions, and the CO2 sequestration per unit area is used as a reference sequence, and the gray correlation analysis method is comprehensively used to carry out research. The results show that the gray correlation of the influencing factors of CO2 stability in goaf is as follows: cover thickness, burial depth, cap continuity, lithology of overlying rock layer, number of cap assemblies, porosity, groundwater salinity, ground temperature gradient, goaf collapse degree and permeability. According to the ranking results, it is concluded that the two factors with the highest correlation degree and stronger correlation between cover thickness and burial depth are the main controlling factors affecting the stability of CO2 sequestration in the goaf.