The invention discloses an oral cavity orthodontic wire with a low-friction-force and anti-corrosion surface and a preparation method thereof. The oral cavity orthodontic wire is prepared through the following method that a nano-silica coating deposits on the surface of an austenite stainless steel wire through an unbalanced magnetron sputtering method. The deposition technological parameters include that for the target silica material, the purity is superior to 99.99%, the sputtering power is 200 w, the flow of diluent gas Ar is 50 SCCM, the working air pressure is 2.0 Pa, and the deposition time is 100 min. By means of the technical scheme, the surface modified layer can improve the friction performance, the corrosion resistance performance and biocompatibility of the surface of the stainless steel wire, and the requirements of surface modification and clinical application of the orthodontic wire are met.