Abstract: With the continuous development of gas trunk pipelines following the trend of high flow rate and high pressure, the safe and reliable operation of gas supply pipeline systems shall meet more requirements. In this paper, a method forevaluating the gas supply reliability of gas trunk pipeline in the accident condition was established referring to Petrobras'sand DNV's gas supply reliability evaluation methods of natural gas pipeline network. In this method, the accident conditionis simulated by using the technological calculation software TGNET to establish the sample set of the limit state functionvalue of gas supply. Sampling is carried out by means of MATLAB to determine the probability distribution model of thesample. And combined with the classification standard of natural gas supply grade, the gas supply reliability of gas trunkpipeline is obtained. Finally, its feasibility was verified based on specific calculation examples. The research results canprovide the guidance for the further study on the reliability of Chinese gas pipeline systems.