Abstract: A submerged arc welding wire for low alloy steel was developed, and Q345B steel plate was used as the base metal for welding. The chemical composition, microstructure and mechanical properties of the welding wire and deposited metal were analyzed. The results show that the chemical composition of the welding wire and deposited metal met the design requirements, the microstructure of the deposited metal was carbide-free bainite, the yield strength of the deposited metal was 560 MPa~590 MPa, the tensile strength was 640 MPa~675 MPa, the elongation after fracture was not less than 25.0%, the section shrinkage was not less than 73%, the Vickers hardness was 225~230 HV, the impact transition temperature was -55~-50℃, and the diffusion hydrogen content of the deposited metal was less than 4.0 mL/100 g.