The invention discloses a self-protecting medicine cored wire material for a large-scale hot-forging die sandwich layer and a preparation method thereof. The medicine cored wire material is prepared from the following chemical components of the medicine core in percentage by mass: 0.24 to 0.4 percent of carbon contents, 0.2 to 0.6 percent of silicon contents, 0.8 to 1.2 percent of managanese elements, less than or equal to 0.02 percent of phosphorus contents, less than or equal to 0.02 percent of sulfur content, 1.8 to 2.5 percent of chromium elements, 1.8 to 2.5 percent of nickel elements, 1.2 to 1.6 percent of molybdenum contents, 13 to 18 percent of vanadium contents, and the balance of iron and impurities. The invention provides the self-protecting medicine cored wire material for the large-scale hot-forging die sandwich layer, so that under a high-temperature reloading extreme operating condition of the sandwich layer material, the elastic deformation and the stress diffusion ability of the sandwich layer are improved, the bonding strength of the sandwich layer and a steel casting mould base body as well as a transitional layer is increased, and the molding quality and the welding technology of the sandwich layer are better.