Abstract: In this paper, high strength low alloy BWELDY960Q steel was welded by using MAG, microstructure and properties of welded joint at different welding specification parameters were studied. The results show that the volume percentage of acicular ferrite in weld metal obviously appears declined tendency after going up with the heat input increase, which reaches maximum at the heat input of 12.32 kJ/cm. The impact toughness of weld metal and fusion zone, tensile strength, elongation rate and shrinkage of welded join are improved due to the quantity change of acicular ferrite in weld metal. Impact fracture of weld metal is character of dimple, equiaxed and parabolic dimples alternatively distribute on section. However, there are many obvious tearing ride and cleavage steps in impact fracture of fusion zone.