Abstract: Based on the mechanism of CO₂ geological utilization and storage technologies and the international authoritative evalua-tion formulae, the methodology of theoretical potential assessment at the sub-basin scale is proposed in this paper, and the solutions of key parameters are provided.Meanwhile, with the Sichuan Basin as a case study, the theoretical potential of depleted oil CO₂ storage and CO₂-EOR, depleted gas CO₂ storage and CO₂-EGR, unmineable coal bed seams CO₂ storage and CO₂-ECBM, and deep saline aquifer CO₂ storage are evaluated respectively.The results show that the total CO₂ storage potential of deep saline aquifers and depleted gas fields CO₂ storage could reach 154.20×10⁸t and 53.73×10⁸t on the average.Because of good traps, high degree of exploration and good infrastructures, depleted gas fields provide a great chance for carrying out demonstration or industrial CO₂ geological storage proj-ects first for the CO₂ resources located in the Sichuan Basin.The methodology of potential assessment of CO₂ geological utilization and storage technologies has great exploring significance for sub-basin scale national potential evaluation and project planning in China.