Abstract: On the premise of assuring the quality of products, constant improvement in contaminated oil cutting method can effectively reduce the volume of contaminaed oil cutting and increase economic benefits of pipeline operation companies. Through analyzing the variation in contaminated oil volume when the contaminated oil passing the stations in the actual operation of the Western Product Pipeline and corroborating with the theoretical variation of contaminated oil volume along the way, the method of adding 50 m³ to the basic volume of contaminated oil of Xinbao Pupm Station which is in the upstream of terminal station to be the target volume of contaminated oil cutting at the terminal station was proposed. This method has been working well in actual operation. When calculating the second cut point, because the density of the following oil can not be predicted accurately in advance, usually the calculation error is large, which may easily lead to issues like the volume of contaminated oil cut is too large or the oil is unqualified, which can be solved by this method.