Aiming at the corrosion failure question of the outdoor high-voltage isolation switch, accelerated corrosion testsusing 5% (mass fraction) NaCl salt spray for materials of Q235 and Q235NH were carried out. By means of the controlled trials method, samples were divided into two groups, and each group contains four specimens. After that, neutral-salt-spray corrosion tests with 60h, 100h, 130h, and 160h were conducted. Finally, the rust layer was observed by a microscope, and the corrosion rate was calculated according to the weight loss method. Experimental results indicated that the rust layer in Q235NH was more compact after being corroded. As a result, it provide more protection for the substrate.