The invention discloses a preparation method of a platinum-magnesium metal composite material. The platinum-magnesium metal composite material is prepared from platinum, ferriferrous oxide, binder, silicon, magnesium, manganese oxide, zirconium oxide, tin, polyester, SMA, HIPS, LCP, stearic acid, cobalt iso-octoate and white oil. The raw material source is wide, the strength is high, the tensile strength is high, the bending strength is high, and the impact strength reaches up to 7000-8000 MPa; the components have a synergistic effect, corrosion resistance is good, acid-base corrosion is achieved, and wear resistance reaches up to 0.0014-0.0018 cm<3>; adaptability is high, heat resistance temperature is high, the high temperature at 1600-1800 DEG C can be resisted, and the breaking elongation reaches up to 600-1000%; and the hardness is high, the components produce the synergistic effect, the Shore hardness is 800-1200, the bending strength is 3500-5500 MPa, the brightness is high, useis convenient, the cost is low, the technology is simple, and wide-range use can be achieved.