Abstract: Rare earth elements have a unique 4f-5d orbital structure, which is easy to form coordination bonds with O and N elements in the polymer structure, thus improving the properties of the polymer. Thermoplastic urethane (TPU) is a good biomaterial due to its structural stability, microbial resistance and similar molecular structure and structure of proteins. Introducing a small amount of rare earth into the polymer material can improve its blood compatibility and biocompatibility and make it exist stably in vivo. In this paper, nano lanthanum oxide (La₂O₃) was used as the research object, and dendritic macromolecules with unique nano cavity structure were used as templates to induce and control the preparation of nano lanthanum oxide with different morphological structures. The La₂O₃/TPU elastomer composites were prepared by introducing rare earth compounds into TPU in-situ bulk polymerization. The biological properties of nano-La₂O₃ /TPU elastomer composites were systematically studied. The results showed that the blood compatibility and biocompatibility of TPU elastomers were significantly improved due to the introduction of nano rare earth.