An aluminized coating of TiAl3 was prepared on Ti-6Al-4V alloy by hot-dip aluminizing and subsequently high-temperature diffusion at 650 ℃. Dry sliding wear behavior was conducted for the aluminized Ti-6Al-4V alloy against GCr15 steel on a pin-on-disc wear tester. The morphology, phase and composition of worn surface of the HDA coatings were characterized by SEM, XRD, EDS and XPS. The wear mechanism was also explored. The research result demonstrated that with an increase of sliding velocity, the wear loss of the aluminized Ti-6Al-4V alloy decreased to a lower value at 0.75 m/s, then increased to the highest at 2.68 m/s and finally decreased to the lowest at 4 m/s. At different sliding velocities, the wear loss increased with an increase of load. Tribo-layers were identified to notably affect the wear behavior and mechanism. At 4 m/s, oxide-containing tribo-layers (TiO and TiO2) possessed an obvious wear-reduced function; conversely at 2.68 m/s, no-oxide ones did not show the protection from wear. Compared with uncoated Ti-6Al-4V alloy, the aluminized coating improved the wear resistance of the titanium alloy under various conditions, especially 4 m/s. The improved wear performance was suggested to be attributed to Ti-Al coating and tribo-oxide layer.