The invention provides an alloy material for a ship valve. The alloy material comprises 0.21-0.3% of C, 0.06-1.0% of Mn, 0.03-0.04% of P, 0.011-0.045% of S, 0.50-0.60% of Si, 0.21-0.30% of Cu, 0.01-0.50%of Ni, 0.48-0.50% of Cr, 0.001-0.002% of Mo, 0.02-0.03% of V, 0.08-0.10% of La, 0.21-0.30% of Pb, 0.011-0.045% of As, 0.01-0.03% of Pr, 0.01-0.03% of Ce, 0.01-0.03 of Ga, 0.01-0.03% of Al, 0.01-0.03% of Zn and the balance of Fe. According to the alloy material prepared by the method, the mechanical strength of rolled steel is enhanced, the corrosion resistance of the rolled steel is greatly improved, and the alloy material has paramagnetism and meets the ocean operation requirements.