Abstract: Process of mathematical model establishment for gas mixing rules model of gas pipeline is introduced by adopting Taylor mixed plug flow model.Based on operating data of 10 gas pipelines at home and abroad, It is considers through the research that mixing factor has greater effect on mixed gas concentration in displacement process of gas pipeline, while roughness of bend and pipe wall have a certain effect on mixing coefficient, and among them, influence of bend on air displacement mixing coefficient is very small for the gas pipeline with length more than 100 km, and the shorter the gas pipeline, the bigger effects the bends have.Roughness of pipe wall has little effect on mixing coefficient of gas, and with the increase of roughness of pipe wall, mixing coefficient of gas increases somewhat.As roughness of pipe wall runs up to 6 times than before, the mixing coefficient only increases 2.6% averagely.