The study of vacuum surface flashover along the insulator ring was carried out. An experimental platform for vacuum insulator stack was built. The influence of flashover among insulator ring on the voltage of the vacuum insulator stack was evaluated by equivalent circuit model. Vacuum surface flashover along the three kinds of material insulator stacks were carried out, which verify the availability and reliability of the experimental platform. This work provides a reference for the engineering research of the vacuum insulator stack of pulse power device, and also provides an experimental platform for research of new insulation materials.