The invention provides an application method of a metal spraying nozzle corrosion-prevention device and belongs to the technical field of metal corrosion prevention. The application method is characterized by comprising the following steps: preparing cationic polyacrylamide PAM into a 0.1 to 0.30 percent water solution to prepare a No. 1 washing solution; adding Lonza polyaminopropyl biguanide toprepare a 10 to 21 percent water solution used as a No. 2 washing solution; adding glycerol emulsion to prepare a 0.05 to 0.5 percent water solution used as a No. 3 washing solution; gradually fully filling into a whole liquid path system and spraying out from a spraying nozzle, so as to discharge water molecules and water which are free in the whole liquid path system or fuse into a corrosion-prevention clearing solution; and forming one layer of a corrosion-prevention clearing solution thin film on a contact part of the metal spraying nozzle and liquid, so as to prevent electrochemical corrosion conditions from being formed by the spraying nozzle and a water through hole of the spraying nozzle and realize corrosion prevention of the metal spraying nozzle and the water through hole of themetal spraying nozzle. The water through hole of the metal spraying nozzle keeps a smooth state all the time, so that the problem that the dry mist dust-inhibition metal spraying nozzle cannot work normally due to corrosion sis also solved.