Abstract: The determination of design throughput for the natural gas transmission pipeline needs to consider the following factors: the resources and the operations of the natural gas fields, the market demand, the users' consumption capability for the natural gas price, the economical properties of the substitution for the gas sources, the influence of the correlative nation policies and so on. On the basis of the construction experiences of long distance gas transmission pipeline at home and abroad, this paper brings forward the research content and methods of the design throughput for the natural gas transmission pipeline. According to the "demand theory" of the economics theory, the design throughput of different pipelines can be determined in allusion to the different prices of gas pipeline transmission. Furthermore, the influences of the different customers' unbalanced demands on the pipeline design throughput are taken into account.