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A surface ceramic protective film was prepared on Ti-6Al-4V alloy using laser-assisted ultrasonic nanocrystal surface modification technology (LA-UNSM). The uniform ceramic protective film, which was comprised of Al 2 O 3 and small amounts of TiO 2 and TiN, showed very strong adhesion to the substrate. LA-UNSM treatment dramatically increased the dislocation density and atomic diffusion rate by introducing thermomechanical activation energy, which further greatly reduced the energetic barriers of the oxide to nitride nucleation and growth. Due to the formation of a ceramic protective film and a nanocrystalline gradient reinforcement layer on the sample surface, the surface hardness was dramatically enhanced after LA-UNSM treatment. The electrochemical corrosion behavior in simulated seawater and the fretting wear behavior of samples were also investigated. The results revealed the ceramic protective film and gradient nanocrystalline layer introduced by LA-UNSM could substantially reduce the corrosion current density by 83 % and the wear volume by 90 % as compared to control samples. These results show that LA-UNSM effectively promotes the corrosion and wear property of titanium alloy through forming a ceramic protective film. [Display omitted] • A surface ceramic protective layer was rapidly formed through LA-UNSM. • Significant surface hardening was achieved through grain refinement, work-hardening and the formation of the ceramic phase. • The corrosion resistance and fretting wear resistance of Ti-6Al-4V alloy were dramatically improved through LA-UNSM. [ABSTRACT FROM AUTHOR]