The invention discloses a high-strength and high-tenacity gas shielded 
welding wire. The 
welding wire comprises the following 
chemical composition in percentage by 
mass: 0.02 to 0.12 percent of carbon (C), 1.20 to 2.10 percent of 
manganese (Mn), 0.20 to 1.00 percent of 
silicon (Si), less than or equal to 0.010 percent of 
sulfur (S), less than or equal to 0.015 percent of 
phosphorus (P), 2.00 to 3.50 percent of 
nickel (Ni), 0.20 to 0.80 percent of 
molybdenum (Mo), 0.20 to 0.30 percent of 
titanium (Ti), 0.60 to 1.20 percent of 
chromium (Cr), less than or equal to 0.05 percent of 
vanadium (V), 0.005 to 0.010 percent of 
boron (B), less than or equal to 0.015 percent of aluminum (Al), less than or equal to 0.35 percent of 
copper (Cu) and the balance of iron (Fe). The 
welding wire is used for welding steels of a strength grade of between 850 and 950MPa; and under the protection of a 
mixed gas (80 percent of 
argon (Ar) and 20 percent of 
carbon dioxide (CO2)), the 
weld metal tensile strength of the welding wire is more than or equal to 850MPa, the yield strength is more than or equal to 720MPa, the elongation is more than or equal to 22 percent, and the low-temperature 
impact toughness Akv is more than or equal to 181J at the temperature of -30 DEG C, or more than or equal to 175J at the temperature of -40 DEG C, or more than or equal to 162J at the temperature of -50 DEG C.