Abstract: To achieve the "dual carbon" goals, repurposing in-service oil and gas pipelines for CO2 transport is a key approach to accelerate development of Carbon Capture, Utilization and Storage (CCUS). Replacing the pipeline medium with CO₂ introduces new risk challenges due to its distinct physical properties. Current pipeline risk assessment systems are inadequate for these engineering requirements. Therefore, research on risk assessment methods tailored to pipelines repurposed for CO₂ transport is essential to address these challenges effectively. Based on oil and gas pipeline risk assessment experience, advances in domestic and international CO₂ pipeline risk assessment technologies were systematically reviewed. The risk characteristics and changes resulting from repurposing in-service pipelines for CO₂ transport were analyzed in depth, and a quantitative risk assessment methodology for such repurposing was developed. Distinct risk levels related to corrosion, crack propagation, and historical defects were identified. The limitations of using natural gas pipeline historical data for failure probability calculations were highlighted, and a probability optimization method combining Bayesian networks and correction factors was proposed. Failure consequence simulations for repurposed pipelines were specified to rely on the geographical information of in-service pipelines, with simulation tools selected based on heavy gas properties and complex terrain. Protection distances were redefined, establishing a quantitative risk assessment system tailored for pipelines repurposed for CO₂ transport. These technical methods provide theoretical and practical support for advancing CCUS projects.