The synergistic antioxidant mechanism of chlorogenic acids (CQAs) was studied in this paper through cyclic voltammograms (CV), oil-water partition coefficient (P), FT-IR, XRD and circular dichroism (CD). The antioxidant capability of CQAs isomers and their mixture was determined by using ABTS free radical quenching ability assay. The results showed that the bigger the antioxidant activity disparity between the CQAs molecules was, the higher the content of high antioxidant activity CQAs was, the better the synergistic effect of the CQAs combination mixture became; The oxidation potential (Epa) of CQAs combination mixture kept constant in the synergistic experiments, which indicted the oxidative coupling interaction don't exist between the CQAs; The charge transferred (Q) and antioxidant activity exhibited high correlation (0.92); the practical Q was higher than the theoretical Q in the synergistic process and this confirmed that the CQAs (dicaffeoylquinic acids) regeneration of high antioxidant activity happened; the CQAs mixture with the absolute difference value of oil-water partition coefficient of 0.13 gave the good interface effect and high synergistic degree; the interaction and the regular arrangement between the CQAs combination were not discovered through FT-IR, XRD and CD. Therefore, the regeneration mechanism of CQAs molecules and the interface effect of reaction system were the main cause of the phenomenon of the synergistic antioxidant of CQAs.