Abstract: By means of visual inspection, chemical composition analysis, mechanical property testing, penetration testing and metallographic examination, the base metal with good surface quality and poor surface quality (qualified and unqualified parent metal) was compared; and the welded structure material with the two kinds of base metal was compared after a operation comparison test in corrosive environment for 2 years. The results showed that the phenomenon of corrosion occurred and corrosion pits were found in the unqualified parent metal and welded joints in corrosive environment; the cracks were formed in the pits on weld fusion line under tensile stress, the non-overload damage type fracture was produced; on the other hand, the phenomenon of corrosion and pits were not found in the qualified parent metal and welded joints.