Abstract: In allusion to the multi-product pipeline with initial contaminated volume, the authors carry out a study on the application of equivalent pipe length method in calculating the terminal contaminated volume of multi-product pipeline, obtain a relationship between the terminal contaminated volume and initial contaminated volume of multi-product pipeline and analyze the influence of variation in pipe diameter and flow rate on the terminal contaminated volume of multi-product pipeline as well. In this paper, calculation results of contaminated volume from different equations are analyzed and compared, and the availability of the equations is presented.