The invention discloses a high-heat-input submerged-
arc welding wire steel 
wire rod and a preparation method thereof, a high-heat-input submerged-
arc welding wire and a high-heat-input 
welding method. The high-heat-input submerged-
arc welding wire steel 
wire rod comprises the following chemical components in percentage by 
mass: 0.04 to 0.06 percent of C, 0.1 to 0.2 percent of Si, 1.4 to 1.6 percent of Mn, 1.0 to 1.5 percent of Ni, 0.02 to 0.04 percent of Nb, 0.02 to 0.05 percent of Ti, 0.0040 to 0.0055 percent of B and the balance of Al, the 
alloy comprises the following components in percentage by weight: 0.004% of Mg, 0.0005-0.0020% of P, less than or equal to 0.005% of S, less than or equal to 0.005% of N and the balance of Fe and inevitable impurities. Through reasonable design of the chemical components and the content, the high-heat-input submerged-arc 
welding wire steel 
wire rod has low carbon equivalent in the 
welding wire preparation process, the low-temperature 
toughness of 
weld metal can be improved, generation of brittle phases is reduced, the 
yield ratio of the 
weld metal is reduced, and the prepared high-heat-input submerged-arc welding wire has good application prospects. The allowable welding heat input is greater than or equal to 300kJ / cm, and a steel plate with the thickness of more than 40mm can be thoroughly welded in a 
single pass.