A phytic acid (PA)-based ternary complex biomimetic nanomaterial consisting of PA, metal ions and a protein/polypeptide is provided, and it is formed by connecting the protein/polypeptide with PA using metal cations as a cation bridge. The PA ternary complex having different protein/polypeptide groups is synthesized with various metal ions as bridges. A novel nanotheranostic probe having high biocompatibility is constructed. The probe may be reassembled and gathered persistently at tumor sites, allowing for the coordination loading of imaging/therapeutic metal ions. This enables long-lasting tumor imaging, treatment or integrated diagnosis and treatment, showing promise as a novel biomimetic nanomaterial in the field of biomedicine. In addition, the preparation process of the nanomaterial is simple and easy for industrial production.