Accurate lifetime prediction of transformer oil-paper insulation is of great significance in ensuring the safe and stable operation of a power system. In this paper, the internal mechanism relationship between interfacial polarization and aging oil-paper insulation is analyzed based on a microscopic dielectric response mechanism. Based on a mixed polarization model, an equivalent circuit topology with an interfacial polarization branch is introduced on the basis of an extended Debye model, and the application of interfacial charge polarization characteristics in oil-paper insulation life prediction is explored. First, the universal relaxation polarization law behind the spectrum changes in the process of temperature rise is analyzed, and the recovery voltage polarization spectrum is reconstructed based on the mixed polarization model. Combined with the influence law of temperature on the principal time constant and model parameters, a calculation method for the activation energy of oil-paper insulation in a single temperature test is proposed. The frequency-temperature translation factor is constructed from the interface polarization capacitance. Secondly, the change rule of dielectric loss factor with the deepening of aging is analyzed, the internal relationship between loss peak shift and relaxation time of interfacial polarization is explored, and a new characteristic parameter in frequency domain, the interfacial polarization branch poleis refined to characterize the polymerization degree content of oil-paper insulation. Finally, an oil-paper insulation life prediction model is constructed by combining interface polarization branch pole, frequency-temperature translation factor and a loss accumulation dynamic equation, and the measured data of a transformer of different operating years are substituted into the model to verify its effectiveness. This provides a new idea for oil-paper insulation life prediction.