A tamperproof genuineness ID device with self-destruct protection function and a method thereof, which identifies whether merchandises are genuine or fake by reading, identifying and encrypting genuineness ID information in a genuineness ID medium. The tamperproof genuineness ID device includes a working part with self-destruct protection function and a detecting work part for identifying a product to be detected, wherein the product to be detected is airtight sealed or fixed with the tamperproof genuineness ID device together. The method includes several steps: setting the genuineness ID medium in a coordinate working state with the tamperproof genuineness ID device; identifying information in the genuineness ID medium by the detecting work part of the tamperproof genuineness ID device, then encrypting and calculating to obtain a native genuineness ID code; and outputting a detecting result. The tamperproof genuineness ID device makes genuineness ID detection for merchandise easier and more reliable.