Abstract: Systematic corrosion tests were conducted on 904 L+ 14 Cr1MoR ( H) and 904 L+Q345R clad plates annealed at 675 ℃.The results showed that the 904 L steel suffered from grain coarsening and precipitating of carbides at ingtergranular boundaries.The critical pitting temperatare of cladding 904 L was equal to or higher than 40℃, but no higher than that of its initial state; its corrosion rate was lower than 11 mm/a; Cracks weren't discovered in the lateral surface of the bending test samples.