Abstract: The effect of transportation order to contamination in uphill pipeline and downhill pipeline are analyzed by means of establishing contamination model. Numerical study on the concentration distribution of contamination in pipeline is investigated with the help of PHOENICS. The computation results show that the effect of density to laminar bottom layer in vertical pipeline is obvious and is bigger than that of viscosity, which can not be ignored. The most important phenomenon that the front oil with small viscosity must not form a smaller length of the mixing-oil than that with the big viscosity is discovered. The study has a theoretical significance for researching on the contamination of batch pipeline in the hypsography area in Western-China.