In order to meet the needs of large capacity, long distance power transmission and nationwide power grid interconnection, China is making great efforts to develop UHV transmission project. Switching overvoltage directly influences the construction cost and operation reliability of UHV transmission system, how to reduce the switching overvoltage deeply is one of the key technical problems that need to be solved urgently. As a new equipment to reduce the switching overvoltage flexibly in UHV Transmission system, the controllable metal oxide surge arrester is being a research hotspot. In this paper, the research status of controllable metal oxide surge arrester technology was introduced, the structure and working principle of controllable switch type metal oxide surge arrester was mainly presented, and the research keystones and application prospect of controllable switch type metal oxide surge arrester in UHV Transmission system were discussed.