Steel for welding structure with excellent marine environment corrosion resistance and manufacturing method of steel

The invention discloses steel for a welding structure with excellent marine environment corrosion resistance. The steel is prepared from the following components in percentage by weight: 0.015-0.060 percent of C, 0.30-0.70 percent of Si, 0.51-1.20 percent of Mn, P no larger than 0.025 percent of P, no larger than 0.005 percent of S, 0.020-0.090 percent of Nb, 0.010-0.050 percent of Ti, 0.26-0.90 percent of Cu, 0.91-1.20 percent of Ni, 0.10-0.60 percent of Mo, 0.005-0.060 percent of Als and the balance of Fe and inevitable impurity elements, wherein Cu/Mo is ensured to be 1.30-1.70, and Si*Mn/Nb is ensured to be 5.0-9.0. The tissue of a steel plate is the tissue of ferrite or ferrite+bainite without the tissue of pearlite. The steel has the yield strength no less than 235-550N/mm and the tensile strength no less than 400N/mm , is mainly applied to large steel structure bridge building in marine environment and can also be used for the field of coastal building structures, offshore oil platforms, marine vessel pipelines, shipbuilding and the like.