Abstract: The Al films were deposited on a titanium aluminum alloy by multi-arc ion plating. The plated titanium aluminum samples were subsequently diffused at 720℃ and 840℃ for 2h, respectively. The microstructures, compositions and phase constitutions of the two diffusion coatings were analyzed using Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and X-ray diffraction (XRD).The microhardness and wear resistance were also measured. The results showed that the diffusion coatings were composed of outer oxide layer and inner diffusion layer, and no Al phase was found in the coatings.The diffusion coatings had higher microhardness and better wear resistance in comparison to the substrate, while the wear resistance of the coatings diffused at 840℃ was superior to the coatings diffused at 720℃.