Abstract: During construction and operation of long-distance natural gas pipeline, pigging operation must be carried out in order to clean impurities within the pipeline to increase smoothness of pipe wall and transmission efficiency of pipeline.Based on the type of the pig used and chosen for actual operating situation in FuNa Gas Pipeline, volumetric method is used to calculate running distance of the pig and correction on calculation model is made by means of mean pressure.In accordance with SY/T5922—2003 《Operating Standard of Natural Gas Transmission Pipeline》, running time of pig is computed with the mean pressure and calculated value and actual arrival time of the pig is 5 min. apart.