In this paper, the magnetostrictive orthogonal calculation method is used to simulate the vibration of iron cores of the transformer and shunt reactor models. The two models have the same size except there is a 2 mm air gap in the middle core of the reactor model. The Maxwell stress and total stress on the two cores are quantitatively calculated. The calculated results show that the air gap has a great influence on the vibration of the shunt reactor core. The Maxwell stress is the main reason for the vibration of the reactor core, but the vibration of the transformer core is mainly caused by magnetostriction. Finally, the experimental platform is built to measure the vibration accelerations of the two models and verify the results of the simulation.