Tightening tool for air conduit and assembling method

The invention discloses a tightening tool for an air conduit and an assembling method. The tightening tool comprises movable clamping jaws evenly distributed in the circumferential direction and a torsion driving mechanism used for being connected with hoisting equipment and a torque wrench; each movable clamping jaw comprises a connecting part used for being connected with the movable end of the torsion driving mechanism, a supporting part used for being inserted into the lower portion of an annular convex edge and a tightening part used for being inserted into an inserting groove, and the movable end of the torsion driving mechanism is connected with the connecting parts of the movable clamping jaws through horizontally-distributed connecting rods; and the two ends of the connecting rods are hinged to the movable end of the torsion driving mechanism and the connecting parts of the movable clamping jaws through vertically-arranged shaft pins correspondingly, and sliding groove in sliding connection with the