Abstract: Due to the multiple effect of compression of water body and quenching,underwater wet welding has some characteristics such as narrow welding process window,poor arc stability and harsh operation.Improving the arc stability and welded joint quality for underwater wet welding is the one of the research hotspots and difficulties.Water glass is rich in potassium,sodium and other low ionization elements,which is an important welding arc stabilizer and surface active substances.The results indicate that pre-coated water glass in the welding groove of workpiece during the underwater wet welding process can generate high ion density and low ionization potential region in the vicinity of the underwater arc,which can achieve a stable arc and wide process window.