The present invention relates to the field of chemical industry, more particularly to a mixed fuel oil reagent for evaluating the oil resistance of a pipeline, and applications thereof, wherein the mixed fuel oil reagent comprises C6-C8 aromatic hydrocarbons, C7-C8 alkanes, and ethers having a formula such as R<1>OR<2>, wherein R<1> is methyl, and R<2> is C3-C4 alkyl. According to the present invention, the reagent has advantages of strong specificity, wide application range, short test period, obvious effect and the like, and can meet the requirements of the existing polyethylene composite pipelines, especially the polyethylene composite pipelines for gas stations.