Abstract: The mixed oil produced in running process of product oil pipeline is difficult to be dealt entirely through back tailtreatment. Factors such as tailing of mixed oil, potentiality of the quality of oil from the oil source, changes in the deliveredproduct oil types, pigging operation and standard of product oil quality all will have effects on the quantity of mixed oil andthe treatment of it. Based on the analysis results, several measures have been gradually taken in product oil pipeline networkof North China, including limiting the minimum batch in order, reasonably arranging the order of transportation, adjustingthe flow direction of oil and controlling the quality of oil adding to it in the process of pipe transportation. During theprocess in station, such technical reformations are carried out, including the switching process transformation of injectionand downloading and increasing the back tail treatment device in intermediate stations. Actual application results indicatethat the above measures can control quantity of mixed oil per batch effectively and increase the ability and flexibility ofback tail treatment of the product oil pipeline network, thus realizing the fully treatment of mixed oil.