In this paper,the welding technology,mechanics and chemistry of the new steel type SQ460 FRW with 28 mm thickness were studied on the basis of welding test,and the welding slope was improved. The differences between pure CO,2, and hybrid gas under the protection of butt flat welding were compared. The process evaluation of flat welding,vertical welding,horizontal welding,vertical welding and cross welding of gas welding joints was carried out. Welding methods,such as simultaneous welding of double-sided double-arc single melting pool,high-speed pulse compression arc technology,and double-sided K-shaped slope 35° +4 mm gap,have been applied in the cross joints. Weld non-destructive testing,mechanical performance testing,macroscopic metallography,different temperature impact test,microscopic metallographic tissue observation and other test content are all qualified,can be used to guide the practical use of subsequent new steel species.