The invention relates to a method for preparing giant magnetoresistance films by a vacuum vapor deposition method. The method adopts a vacuum film plating machine capable of carrying out vapor deposition of metals and oxide materials of various melting points, and comprises the following steps: polishing a SiO2 substrate; boiling the mixed solution of ammonia, hydrogen peroxide and deionized water, and washing by using deionized water; boiling the mixed solution of hydrochloric acid, hydrogen peroxide and deionized water and washing by using deionized water; carrying out ultrasonic and non-ultrasonic deionized water medium normal-temperature and heating polishing cleaning; drying inside a nitrogen furnace; and bombarding the surface of the substrate for cleaning by an ion gun inside a vacuum chamber. In a low-temperature environment, a magnet is arranged on a glass substrate to ensure that the to-be-plated glass substrate is positioned inside a stable magnetic field all the time during film plating; and the atomic weight ratio of a vapor deposition film material is controlled by a compensation type so as to ensure that a finished film obtained through vapor deposition has ideal consistency between alloy components and expected proportion and transverse uniaxial magnetic anisotropy in a short direction. The method is characterized in that the method has simple and easy process,low preparation cost and ideal consistency of the alloy components of a finished film and expected proportion; and the prepared FeSiB film is uniform, compact, stable and firm.