The invention discloses functional albumin and a preparation method of a nano preparation of the functional albumin. The nano preparation of the functional albumin consists of the functional albumin, metal ions and a drug; the metal ions can simultaneously form coordination bonds with the functional albumin and the drug, and can form nanoparticles through induced self-assembly. The nano preparation, through an endocytosis mediated by an albumin receptor (SPARC) on the surface of tumor cells, can deliver the drug into the drug-resistant tumor cells, so as to effectively avoid the exocytosis effect of a p-gp pump on the drug, and then as the coordination bonds break in an acid tumor cell environment through a pH responsibility, the drug releases in cytoplast, enters cell nucleus and inlays in DNA so as to inhibit the synthesis of nucleic acid; and therefore, the growth of the tumor cells is inhibited. Through in vitro characterization, the nano preparation can achieve the relatively good pH responsibility; and through activity evaluation on a cellular level, the system is capable of effectively delivering the drug into the cells, so as to achieve relatively good pH responsive release.