Abstract: Geological storage of CO₂ technologies has become an important and effective method for reducing the emission of greenhouse gases, while its safety in terms of CO₂ leakage has always been an eminent issue for concerns. In this paper, the trapping and sequestration mechanisms of CO₂ in various geological structures are described, and the potential pathways for CO₂ leakage and the related control factors on leakage risks are analyzed and assessed based on case studies and review of the literature. The geological structures analyzed in the paper include depleted oil and gas reservoirs, deep saline aquifers, coal seams and offshore hydrate-bearing sediments. Storage of CO₂ in depleted oil and gas reservoirs has the highest confidence in safety,though the failure of wellbore may cause CO₂ leakage, but their gas sealing capability has been proven during the trapping of oil and natural gas, and it can provide an economic bonus if CO₂ EOR process is considered. This scheme can be adopted for CO₂ disposal in short and medium terms because the storage potential of available oil and gas reservoirs is limited. The storage in saline aquifers involves many trapping mechanisms; therefore there are many potential pathways for CO₂ leakage and unknown factors, leading to relatively high risk of leakage. But due to wide distribution of saline aquifers and their enormous storage potentials, this scheme can be the most promising method for CO₂ sequestration in future. The trapping mechanism of CO₂ in coal seams is mainly dependent on gas adsorption, which is sensitive to the variation of hydrostatic pressure in coal bed, and may result in desorption and gas leakage if it is disturbed during coal mining operations, imposing a relatively high leakage risk. The storage of CO₂ in coal seams can also affect the future use of the coal resource. The storage of CO₂ in offshore hydrate-bearing sediments is thermodynamically feasible, but due to the shallow burial depth and lack of geological trapping, it may pose a high risk for leakage. The injection of CO₂ into the hydrate stability zone is also difficult, so this scheme needs further study and concerns.