In recent years, with the growing demand for carbon capture and storage, CO2 transmission pipelines have emerged as a key infrastructure, with a clear trend towards large-scale development. CO2 can be transported in pipelines through gaseous state, supercritical state or dense phase state. For long-distance CO2 transmission pipelines, the supercritical transportation mode is more economical compared with gaseous transmission. Compared with conventional oil transmission pipelines, supercritical CO2 transmission faces issues such as phase change, water hammer effect, and overpressure during the transmission process. Affected by its physical properties and transmission technology, its flow assurance deserves systematic discussion. Based on the supercritical CO2 transmission process and its operating characteristics, this study identifies key aspects of flow assurance analysis for supercritical CO2 pipelines. It explores the overpressure issues due to water hammer and thermal expansion between supercritical CO2 and conventional oil products. Additionally, it specifically conducts a study on the phase change and temperature distribution in the planned blowdown of supercritical CO2 in the pipelines. Research shows that the impact of water hammer overpressure on supercritical CO2 pipelines is relatively minor, but risk of decompression phase change downstream of the water hammer point do exist; moreover, stopping the flow in the supercritical CO2 pipeline can lead to thermal expansion and overpressure issues; and terrain influence can cause uneven phase change and temperature distribution during blowdown. Therefore, the planning for the blowdown of supercritical CO2 pipelines should incorporate numerical simulation analysis, and the temperature monitoring procedure during this process requires additional research. The research results can provide relevant reference for the design and operation of supercritical CO2 pipelines.