The invention discloses a method for preparing magnetic metal-metal core-shell nano particles, which relates to metal nano particles. The method comprises: dissolving chloroauric acid and triphenylphosphine in ethanol respectively, filtering, cleaning, drying, obtaining an organic compound formed by gold and triphenylphosphine, mixing the organic compound with alkylamine, obtaining solution A, mixing an organic solvent A with a noble metal salt, adding mixed solution A, rising the temperature to perform a reaction, cooling and obtaining magnetic metal nano particles; dissolving the obtained organic compound formed by gold and triphenylphosphine in an organic solvent B, injecting obtained magnetic metal nano particles, keeping the temperature between 120 and 160 DEG C for 20 minutes to 1 hour, reducing to obtain gold and wrapping gold on the formed magnetic metal nano particles and obtaining nano particles in which gold and magnetic metal are in a core-shell structure; and washing the nano particles in which gold and magnetic metal are in a core-shell structure, performing centrifugal separation, drying and obtaining powder product, namely magnetic metal-gold core-shell nano particles.