In this study the microstructure and mechanical properties of stainless steel clad plate are researched. Due to element diffusion (Fe, Cr, Ni, Mn), a 20 μm thick diffusion layer is formed between stainless steel and carbon steel clad plate. The diffusion layer has a stable mechanical performance without obvious grain microstructure, and its internal mechanical properties show a graded change in the thickness direction. This is beneficial to a strong bond between stainless steel and carbon steel and the stable transition of mechanical performance in the thickness direction, as well as further carbon diffusion changes in the microstructure and mechanical properties near the diffusion layer of clad plate. Carburization stainless steel with a thickness of 150 μm is formed in the stainless steel side and decarburization carbon steel with a thickness of 80 μm is formed in the carbon steel side.