Fe-based soft magnetic composites have important applications in reactor core manufacturing due to their superior magnetic properties. In this paper, the vibration noise characteristics of the reactor with core made of this material are investigated and simulated and optimized by finite element method. First, a three-dimensional finite element model of the reactor is established to analyze the electromagnetic force distribution and vibration displacement velocity, and then the accuracy of the finite element analysis model is verified by combining the simulation experimental data. On this basis, the oxidation time parameters of the Fe-based soft magnetic composite material are adjusted, and the optimal parameters are selected to improve the vibration of the reactor, so as to achieve the purpose of improving the working condition of the reactor. The results show that the magnetic loss and other properties of the material have an important influence on the core vibration, and the reasonable optimization of the composite material structure parameters can reduce the vibration amplitude of the reactor and effectively suppress the noise. This study provides a theoretical basis for the design and optimization of this type of reactor.