Abstract: Excessive electro-dynamic repulsion force will be generated between the contacts during the breaking and closing process of vacuum interrupter, which aggravates the contact bounce phenomenon, causes high temperature arc to ablate contacts, thus affects the working performance of the vacuum interrupter. In this study, the 3D model of vacuum interrupter is established, and the cylindrical conductive bridge model is introduced as the contact point to simulate the current shrinkage between contacts, and the Ansoft Maxwell software is adopted to calculate the electrodynamic repulsion force between dynamic and static contacts. Then the contact structure is optimized to reduce the electrodynamic repulsion force. The results reveal that, when the contact is closed, the direction of Lorentz force and Holm force is opposite, and there exists a suitable contact force which can reduce the total electrodynamic repulsion force to 0 N. The electrodynamic repulsion force decreases with the increases of the number of slots, the rotation angle of the cup finger, and the slot length of the contact plate. Among the four kinds of iron core structure contacts, the annular iron core is best, which can effectively reduce the electrodynamic repulsion force between contacts and improve the magnetic field characteristics of contacts.