Abstract: In order to identify the critical hazard sources based on condition and ensure the safe and smooth transportation of natural gas along the Sichuan-to-East Gas Pipeline, its accident risks shall be evaluated. In this paper, a Falut Tree and Bayesian Network based risk analysis method for pipeline accident was developed. In this method, the clear causal modeling ability of Fault Tree and the strong dynamic updating ability of Bayesian Network are combined together. According to the design, operation and maintenance data of the Sichuan-to-East Gas Pipeline, the causal model for its accident was established. Then it was mapped into the Bayesian Network for analysis. It is shown that the accident risk level of the Sichuan-to-East Gas Pipeline is 1×10^-3 and the corrosion is the top one risk factor leading to the accident of Sichuan-to-East Gas Pipeline. And finally, 5 critical failure causation chains were figured out based on probability updating analysis. The obtainment of key risk factors and failure causation chains is instructive for the hazard source identification and the risk prevention in the pipeline operation site, but it is still not accurate enough. Therefore, it is necessary to carry out further statistical analysis on the probability data of basic failure events to achieve a more accurate risk analysis result.