The invention discloses a metal surface micro-patterning method. A transparent liquid medium not reacted with metal is adopted as protecting liquid; and in particular, when sodium hydroxide solution is adopted, the quick degradation of magnesium in water is prevented, and the machining of a magnesium alloy material by femtosecond laser filamentation in water is realized. When a flowing liquid filmis adopted, the heat dissipation condition of the periphery of a machined part can be prominently improved; and meanwhile, bubbles generated in machining are taken away to prevent accumulation of chips, so that the self-cleaning in the machining process is realized. In addition, compared with high-energy femtosecond laser filamentation in air, on the basis of guaranteeing the machining quality ofa metal surface micro-nano structure, the machining precision can be prominently improved to reach about 10 microns, and meanwhile, the production equipment cost is reduced. More importantly, an active oxidation atmosphere formed by femtosecond laser in the air is prevented, and oxides in machined products are prominently reduced, so that the metal surface and the microcosmic substance forms in machined grooves are not changed to the greatest extent.