Abstract: Deep coal underground gasification coupled CO₂ storage （UCG-CCS） is a key technology to achieve clean coal development and carbon emission reduction. While improving the utilization rate of combustion cavity, the geological storage of CO₂ has the characteristics of good injection, complex sealing, saving transportation cost and great storage potential, etc., and has become a hot spot in CO₂ storage research in recent years. In this paper, the research progress is systematically reviewed from four dimensions: mechanism research, stability evaluation, storage efficiency and leakage monitoring: ① The depth and temperature of deep coal underground gasification combustion cavity are conducive to supercritical CO₂ storage, and the high permeability of combustion cavity can ensure good CO₂ injection; Gasification residue, ash and caved rock have adsorption and mineralization ability. The long-term interaction with the salt water layer in the combustion cavity is conducive to CO₂ dissolution and storage. ② The cavity tightness is affected by multiple factors, and is related to the thickness of the gasification coal seam, the width of the gasification surface, the width of the retained coal pillar, the depth of the formation and the geological structure, etc. The comprehensive design of the gasifier structure ensures the tightness; The CO₂ injection pressure should be controlled to avoid breaking through the cap pressure. The long-term transport of CO₂ geologic storage depends on the long-period numerical simulation and engineering observation. Injection Wells and production Wells are important ways of CO₂ leakage. ③ The storage capacity of underground coal gasification depends on the shape of the combustion cavity, gas production and gas production components. At present, an accurate CO₂ storage capacity evaluation model for underground coal gasification and gas storage is urgently needed. ④ Leakage monitoring and environmental risk assessment is an essential risk control link for engineering CO₂ storage. CO₂ storage requires long-term monitoring of surface deformation, wellbore leakage and pollutant migration, but faces challenges such as formation heterogeneity, high-temperature corrosion, signal attenuation, etc., and needs to build a multiphase seepage model and environmental sustainability index evaluation system to ensure safety.