Ti-Al amorphous composite coatings were prepared at room temperature on the Ti6Al4V (TC4) substrates surface by means of mechanical alloying (MA). XRD, SEM, EDS and micro hardness test technique were employed to investigate surface phase, cross-sectional microstructures and micro-hardness of the coatings. The results show that the coatings are formed via a combination of cold welding, deformation and fracture processes. The coating thickness increased first, then decreased and finally verged to a constant value with increase of milling time; the as-synthesized coatings showed structures with high apparent density and free of porosity. Ti-Al amorphous composite coating, ~200 μm thick, was obtained when rotation speed was 400 r/min and milling time was 12 h. Meanwhile, it was also found that the maximum hardness HV0.1 value of the coating achieved 5800 MPa, which was about threefold higher than that of the substrate. The volume content of the amorphous phase in the coating amounted to 49.53% and 96.35% analyzed by the calculation of the X-ray diffraction intensity curve information when milling time was 6 h and 12 h respectively.