Abstract: The rule of reduction of major quality indicators of oil in the oil products pipeline is studied. In the case of Lanzhou-Chengdu-Chongqing Pipeline, oil products in the same oil tank of the same batch from the initial pump station are tracked, sampled and assayed, the rule of change of final boiling point of gasoline and flash point of diesel during batch transportation is summarized, and the factors influencing change of related parameters are analyzed. The study indicates that during batch transportation, the flash point of diesel has reduced by 4 ℃ on average, the final boiling point of gasoline has risen by 15 ℃ on average, and interblend is the major factor affecting reduction of oil's quality indicators. As a result, realistic suggestions are given as to the quality indicators of oil entering the initial pump station of Lanzhou-Chengdu- Chongqing Pipeline, which have provided theoretical help and practical guidance for improving the quality of oil.