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The surface treatment technique of laser shock processing (LSP), also known as laser peening, was applied to treat the surface of Ti-6Al-4V titanium alloy, which was widely used in many fields including aeronautic industry. The high pressure shock wave (GPa level) and high strain rate (>106 s-1) for laser shocking make it possible to realize the grain refinement even nanocrystallization on the surface of Ti-6Al-4V alloy to improve the performance of material. However, the investigations of self-nanocrystallization of Ti-6Al-4V induced by LSP are seldom reported by now. The advantages of LSP technique is high peak value power, short duration (nano second level), easily realizing and repeated operating. The pressure model of plasma shock was carried out considering the left absorbing layer for the LSP, which is in accordance with the practical situation with more accurate calculation results than previous model. The self-nanocrystallization of titanium alloy surface can be realized using the method of laser shocking. The results enrich the theoretical basis, present a practice method of self-nanocrystallization of material surface and no other impurities are introduced and the performance of fretting wear resistance is improved simultaneously