Abstract: The present application relates to the technical field of electromagnetic-isolation shielding materials, and in particular to a heat-resistant nanocrystalline magnetic-isolation shielding material and a preparation method and application thereof. The preparation method includes the following steps: S1, applying a double-sided adhesive tape onto a nanocrystalline soft-magnetic alloy ribbon to prepare a adhesive-coated nanocrystalline ribbon; S2, performing primary magnet cracking treatment on the adhesive-coated nanocrystalline ribbon to obtain a single-layered nanocrystalline magnetic layer; S3, performing multi-layer combination on the single-layered nanocrystalline magnetic layer to obtain a composite, and performing stress relief treatment on the composite to obtain a multi-layered nanocrystalline magnetic layer; and S4: performing secondary magnet cracking treatment on the multi-layered nanocrystalline magnetic layer to obtain a heat-resistant nanocrystalline magnetic-isolation shielding material.