Abstract: Polyphenylene oxide (PPO) is an important material in industries such as new energy storage and 5G communication. The calculation of thermogravimetric kinetic parameters is the key to quickly evaluate the thermal life of PPO. However, the thermogravimetric analysis usually selects nitrogen atmosphere and high heating rates, which could cause the aging mechanism to change. Therefore, the actual aging process of PPO is simulated by thermogravimetric experiment under slow heating rates and air atmosphere. The Doyle coefficient is modified by fitting the numerical solutions of temperature integral in the interval of failure temperatures corresponding to multiple heating rates. Kinetic analysis is carried out in the early thermo-oxidative degradation stage to get the activation energy of PPO, and the reaction mechanism function during this stage is estimated to calculate the pre-exponential factor. The results show that the accuracy of this method is higher than that of Flynn-Wall- Ozawa method and ASTM E1641-18 method in solving the activation energy, and the actual thermo-oxidative aging of PPO can be equivalent to a single reaction following the quasi-power law reaction mechanism function, according to which, the calculation of the pre-exponential factor is more reliable than the standard method where the model of a chemical first-order reaction is preset. The above work provides an effective technical method for the calculation of thermo-oxidative aging kinetic parameters of polymer insulation.