Abstract: Electrically triggered vacuum surface flashover switch (VSFS) has the advantages of high conduction speed, high insulation recovery speed, small size and simple structure, which make them suitable for high voltage and high power conversion. Conduction speed and stability are important indicators of VSFS output performance, and the study of their influencing factors determines the optimization direction of VSFS. In this paper, the effects of structure, material, and trigger polarity on the output performance of vacuum surface flashover switch are investigated. The results show that the bulk structure has faster and more stable conduction speed compared with the chip structure. Barium titanate dielectric and aluminum nitride dielectric have stable pulse breakdown voltage and are suitable as trigger dielectric. Quartz has a high DC withstand voltage and is suitable for the main gap medium. The output index of the switch in positive triggering mode is better than in negative triggering.