Abstract: A Cu-Al interdiffusion layer was formed on the surface of Mn-Al bronze corroded by liquid metal aluminum.The best aluminum-copper composite interfacial diffusion layer was obtained at the corrosion temperature of 720 ℃, 4wt%KF plating aid and 10 min corrosion time by orthogonal experiment. The morphology, composition and toughness of the composite interfacial diffusion layer were analyzed and characterized by XRD, SEM, EDS, XPS and nano-indentation instrument. The results show that the corrosion interface is composed of uniform corrosion layer, the interface is metallurgical bonding interface, and the precipitated phase of the interdiffusion layer is mainly CuAl₂ phase. The thickness can reach 120μm, the hardness is 2 times higher than that of the manganese aluminum bronze matrix, and the corrosion diffusion layer has good hardness and toughness.