Ultralow-temperature Coriolis mass flowmeter sensor

The ultralow-temperature Coriolis mass flowmeter sensor comprises a flowmeter sensor body shell, a welding nut, a first O-shaped sealing ring, a sealing plug, a vacuumizing sleeve, a screwing shaft, a second O-shaped sealing ring and a vacuumizing pipeline connector. A vacuumizing sleeve is arranged on the outer side of the welding nut, a first O-shaped sealing ring is arranged at the connecting position of the vacuumizing sleeve and the welding nut, the upper end of the screwing shaft is in fastening connection with the vacuumizing sleeve through a second O-shaped sealing ring, and the sealing plug is matched with the screwing shaft. A through hole is formed in the side wall, close to one side of the welding nut, of the vacuumizing sleeve, a vacuumizing pipeline connector is arranged at the position of the through hole, air in the flowmeter sensor body shell is extracted through the vacuumizing pipeline connector connected with a vacuumizing system, and after the specified vacuum degree requirement is met, t