Abstract: The important information and data of YongHuNing Crude Oil Pipeline are introduced, including the property of crude oil and process flow, the mechanism of contaminated product formed, the techniques of decreasing the contaminated product and some methods to track the interface of contaminated product. This paper provides some methods to track the interface of contaminated product during the batch transporting different imported crude oils and the empirical equations suitable to this pipeline to calculate the length of contaminated product. The paper also gives the guideline to cut the interface of contaminated product in line with the property of imported crude oils.