In product oil pipeline batch transportation, mixed oil will be inevitably formed and oil mixture volume decrease becomes indispensable for oil product pipeline operation and management. Calculated is the oil mixture volume at Zhengzhou station in Lan-Zheng­Chang oil product pipeline, conducted is comparative analysis on the actual oil mixture volume data obtained at Zhengzhou station in recent two years and found out is the cause of actual large cutting volume at the station: unreasonable shutdown interface position and long valve stroke time. Proposed are such suggestions as change of one manifold into two manifolds for oil delivery in the tank area, addition of a density meter, decrease of the number of shutdown and unification of density meter calibration.