Welcome to the 31st International Symposium on Discharge and Electrical Insulation in Vacuum (ISDEIV) The International Symposium on Discharge and Electrical Insulation in Vacuum (ISDEIV) is a non-profit, international forum whose purpose is to encourage the advancement of the science and application of electrical insulation and discharges in vacuum, primarily by conducting symposia for the exchange of scientific information. The Symposium is held biennially for the exchange of results, presentation of progress, and discussion of ideas and challenges for the future of discharge and electrical insulation in vacuum. Both fundamental and applied aspects are covered. Symposium program consists of invited talks, invited oral contributions, and posters. Minicourses and informal discussions on relevant topics may also be offered in addition to the regular Symposium schedule. The 31st ISDEIV will be held in the beautiful city, "The land of abundance", Chengdu, China, from Sept. 21 to 26, 2025. The conference will be hosted by Sichuan University, and technically sponsored by IEEE DEIS. In the meantime, please contact us if you have questions on any aspect of the conference. ISDEIV is an international forum with a long history of scientific exchange and advancement. Since the first Symposium in 1964, ISDEIV has been held every 2 years. The vision for ISDEIV is to encourage the advancement of the science and application of electrical insulation and discharges in vacuum, primarily through exchange of scientific information and data exchange. Over the past 60 years, ISDEIV has played an important role in advancing scientific progress, fostering technological innovation and application, and cultivating young talent in the field. All the registered and PRESENTED papers will be included in an IEEE Xplore collection (EI Index), and recommended to submit to an IEEE TPS Special Issue. Topics Over the years, the scope of ISDEIV has been adjusted to drive innovation on the most important topics in vacuum discharge and insulation science, with current topics of interest including, but not limited to: A: BREAKDOWN AND FLASHOVER A1. Vacuum breakdown and pre-breakdown phenomena A2. Surface discharges and flashover phenomena B: VACUUM ARCS B1. Switching in vacuum and related phenomena B2. Interaction of vacuum arcs with magnetic fields B3. Vacuum arc physics B4. Modeling and simulation B5. Pulsed power physics and technology C: APPLICATIONS C1. Vacuum interrupters and their applications C2. Surface science and modification and related technologies C3. Electron, ion, neutron, X-ray and other beam and light sources C4. Accelerator and fusion reactor related issues C5. Space related technologies C6. Vacuum microelectronics and their applications D: OTHERS ……