Abstract: By using laser wire - feeding welding method and without removing the galvanized layer, the welding of thin steel plates of galvanized air ducts is achieved. The microstructure and mechanical properties of the joints are observed through a metallographic microscope and an electronic universal testing machine. The research shows that within the process range of laser power from 3020 to 3340 W, welding speed from 4 to 8 mm/s, wire feeding speed from 1.8 to 2.2 m/min, and defocus amount from +3 to +7 mm, ferrite and martensite in the weld zone and heat - affected zone are evenly distributed. When the laser power is 3180 W, the welding speed is 7 mm/s, the wire feeding speed is 2.0 m/min, and the defocus amount is +5 mm, the tensile strength of the joint can reach a maximum of 30.96 kN. It is detected by EPMA (Electron Probe Micro - Analyzer) that there is no zinc element in the weld, indicating that zinc vapor does not affect the welding during the laser welding process.