Abstract: The vacuum sealing joint is a kind of equipment which connects the cryogenic and vacuum equipment and vacuum extractor，its reliability directly affects the vacuum result，leak rate and vacuum life length.The present vacuum sealing joint use double seal and the sealing cap is brazed to the vacuum tube，so its tightness has low reliability and service performance.This paper presents a new kind of vacuum sealing joint by optimum analysis，improvement design and confirmatory test，the adaptive design is not only improving the vacuum life length but also supplying the security of the cryogenic liquid fueling system.