This paper prepares low molecular weight polyphenylene ether through a redistribution reaction and analyzes the influence of the mass factor of the initiator benzoyl peroxide (BPO) in the reaction system on the molecular weight of the product polyphenylene ether. The molecular structure of the low molecular weight polyphenylene ether is characterized using infrared spectroscopy. The relative molecular mass of each product is measured and calculated using the viscosity method. Differential scanning calorimetry (DSC) is used to measure Ti, Tp, and Tf of the modified polyphenylene ether composite system, and then the activation energy Ea, frequency factor A, and reaction order n are calculated through relevant equations. The curing reaction kinetics equation is derived from Ea, A, and n. Finally, data analysis reveals that there is only one curing peak in the curing process of all samples, and the curing reaction is approximately a first-order reaction, indicating good compatibility between PPO and BNE-200.