Abstract: Objective: To analyze the environmental conditions of(-)-epigallocatechin-3-gallate(EGCG)oxidative polymerization and the effects of changes in its stability on the redox balance of the test cells,and to lay the foundation for an in-depth study of the role of EGCG in cell culture systems and living organisms. Methods: The research set different conditions of solution environment,EGCG concentration,temperature,time,pH,to evaluate the difference of EGCG oxidative polymerization under different conditions by detecting the change of OD₅₇₈ value. Result: The results showed that RPMI1640 and DMEM medium were more favorable for EGCG oxidation polymerization than H₂O. High temperature and high EGCG concentration and alkaline conditions promoted EGCG oxidation polymerization. At the same time,the oxidative polymerization of EGCG intensified with the extension of the reaction time. In a cell-containing culture system,EGCG also underwent auto-oxidative polymerization and produced H₂O₂,which increased the H₂O₂ concentration inside and outside the cell. However,the intracellular H₂O₂ concentration showed a trend of first increase and then decrease. Conclusion: Solution environment and pH changes are the key factors that cause EGCG oxidative polymerization. 20 μmol/L EGCG is more conducive to exert antioxidant activity through oxidative polymerization effect in cell culture.