The invention discloses a modified compound for an anti-corrosion sealing ring and a preparation method thereof. The preparation method comprises the following steps: 1) performing contact reaction ona carbon fiber, cyclodextrin, a silane coupling agent and water, and then filtering, taking a filter cake and drying, thereby acquiring a modified carbon fiber; 2) performing hydrothermal reaction onthe modified carbon fiber, silver salt, zinc salt, urea and water, and then filtering, taking the filter cake and lastly calcining under the existence of shielding gas, thereby acquiring a compound carbon fiber; 3) mixing the compound carbon fiber, shell powder, attapulgite, silicon carbide and rare earth oxide, thereby acquiring the modified compound for the anti-corrosion sealing ring. The modified compound prepared according to the method is capable of greatly improving the acid-resisting and alkali-resisting properties of the sealing ring. The preparation method has the advantages of simple process and easily acquired raw materials.