The utility model discloses a high temperature vacuum furnace manages floated sealing device, including the sealing device body, the sealing device body is established including the cover metal stoveouter covering on the boiler tube, boss sealing flange and setting the seal receptacle stove outer covering terminal surface and boss sealing flange between of setting on the boiler tube terminal surface all be provided with annular flexible extension pieces between seal receptacle and the stove outer covering terminal surface, the extensible member can stretch out and draw back along self axis, and the extensible member cover is established on the boiler tube, its both ends are connected with seal receptacle and stove outer covering terminal surface respectively, and form the annular space between extensible member and the boiler tube. When ceramic boiler tube expanded, the extensible member was by drawing to produce one with the axial inflation of ceramic boiler tube opposite direction'spulling force, the ceramic pipe produced when reducing ceramic boiler tube inflation then expansion stress in order to prevent the breakage of bursting apart of ceramic boiler tube, protects the intensity of ceramic boiler tube.