At present, there are few studies on the influence of antioxidants on the protective effect of transformer oil paper insulation system and passivator. Therefore, the widely used antioxidant DBPC(dibenzyl disulfide), passivator Irgamet 39, sulfides dibenzyl disulfides and dodecyl mertan were selected and simulated by reaction molecular dynamics. By measuring the van der Waals energy, mean square displacement, elastic modulus and the number of hydrogen bonds, the effects of different contents of antioxidant DBPC molecules on the insulation properties of oil paper and the protective effect of passivating agents were studied. The results show that the amount of DBPC should be added according to the standard, that is, the antioxidant content in the transformer is between 0.15% and 0.3%. If it is greater than or less than this range, it will accelerate the aging of oil paper insulation to varying degrees and reduce its insulation performance. The DBPC-Cu complex produced by DBPC dissolves in the insulating oil, and then the cuprous sulfide is deposited on the insulating paper. Even if the content is added according to the standard content, the insulation performance of the insulating paper will be slightly affected. If DBPC is added according to the standard of 0.15%~0.3%, it has little effect on the insulation performance of the transformer oil-paper insulation system, and has almost no effect on the protection effect of passivator.