The invention discloses a method for maintaining a nozzle cavity mouth of an air jet loom. The method comprises the following steps: (1) manufacturing of a correcting tool: the correcting tool comprises a handle and a conical needle; the conical needle is aligned to the nozzle cavity mouth; the handle of the correcting tool is rotated to enable the conical needle of the correcting tool to rotate into the nozzle cavity mouth; and the nozzle cavity mouth is returned to an original aperture; (2) manufacturing of a rough polishing rod: the rough polishing rod is to paste and wrap an abrasive paperof 400-600 meshes on a circular metal rod, and is assembled on an electric grinding machine for roughly polishing the nozzle cavity mouth; (3) manufacturing of a fine polishing rod: the fine polishing rod is to paste and wrap an abrasive paper of 800-1200 meshes on a circular metal rod, and is assembled on the electric grinding machine for finely polishing the nozzle cavity mouth; and (4) manufacturing of a finish polishing rod: the finish polishing rod is to paste and wrap an abrasive paper of 2000-3000 meshes on a circular metal rod, and is assembled on the electric grinding machine for finish polishing of the nozzle cavity mouth. The method has no need to replace a new nozzle, so that the cost is reduced.