Abstract: The paper reviews the application of gas pipeline design coefficient in the Class I areas abroad, and analyzes the impacts of design coefficient on the pipeline reliability. The results show that improving the design coefficient may increase pipeline failure probability and operational risks, which still could be accepted yet. In view of the specifications of X80 steel pipe used in the 2nd West-to-East Gas Pipeline Project, the pipeline quality in China has been proved to be advanced in the world, which is the prerequisite of improving pipeline design coefficient in the Class I areas. The paper hereby presents some key performance indexes and requirements of quality control for a pipeline with design coefficient of 0.8. It is considered that by means of further improving the steel pipe performance and researching the relative supporting technology, increasing the design coefficient for the gas pipelines located in the Class I areas is necessary, and meanwhile, based on the 3rd West-to-East Gas Pipeline Project, speeding up the construction of pipeline test sections and revising the GB50251, a gas pipeline engineering design specification, can lay a foundation for the engineering application of design coefficient of 0.8 to long-distancegas pipelines with large diameters.