Abstract: The different gas displacement scenarios for Sebei-Xi'ning-Lanzhou Gas Transmission Pipeline to be commissioned are compared and analyzed. This paper describes the advantages and disadvantages of use-separation-pig and non-use-separation pig and the feasibility of non-use-separation pig scenario. A qualita-tive analysis on the measurement data is made and common law is summarized. Based on the analytical result, the authors present a gas displacement technique for the commissioning of long distance and big diameter gas transmission pipeline.