Abstract: SOI LDMOS device is the core of SOI HVIC,and the vertical breakdown voltage is the key to restrict its performance.First,this paper points out the reasons for the low vertical breakdown voltage of conventional SOI LDMOS;Then the vertical voltage-sustaining theory of SOI high-voltage device are introduced,and the operating principle of the three methods to improve the vertical voltage-sustaining technology of SOI device（Ultra thin SOI、Interface charge、Low k Dielectric） are analyzed;After that,based on those three technology,the research work in respect of the SOI vertical voltage-sustaining in recent years are classified and summarized,also their merits and drawbacks are analyzed;Finally,the development of the future vertical voltage-sustaining technology are prospected.