Abstract: Welding experiment was carried out on FV520(B) steels, and then different heat treatments were carried out on base metal and welded joint. Then corrosion experiments of base metal and welded joint were executed in 10wt% H₂SO₄ solution to study the effects of heat treatment processes on corrosion resistance of welded joint. The results show that, after different heat treatments, the surface corrosion morphology of FV520(B) steel welded joint was relatively uniform, but deep fault and ravined corrosion pits were found near the fusion zone. Under the same heat treatment conditions, the corrosion rate of base metal was higher than that of the welded joint. The corrosion resistance of welded joint and base metal could be improved through adding intermediate treatment between solid solution and aging processes. After intermediate treatment at 850℃, the welded joint owned more uniform surface morphology than the welded joint after intermediate treatment at 750℃.