The invention discloses a high-temperature resistant anti-corrosion pump valve sealing gasket and a preparation method thereof. The sealing gasket comprises the following raw materials in parts by weight: 60-70 parts of methyl vinyl silicone rubber, 20-30 parts of ethylene-propylene-diene monomer, 10-15 parts of polyethylene, 1-2 parts of a corundum powder, 5-10 parts of hydroxyl silicone oil, 15-20 parts of fumed silica, 2-3 parts of dihydroxydiphenylsilane, 2-3 parts of zinc oxide, 1-2 parts of alkylated diphenylamine, 4-8 parts of polyethylene wax, 0.5-1 part of 2,4-dihydroxy benaophenonel, 8-12 parts of nano argil, 10-15 parts of modified nano-diamond, 1-2 parts of triallyl cyanurate, 1-3 parts of vinyl-tris(beta-methoxyethoxy)silane, 1-2 parts of an accelerant CZ, 2-3 parts of an anti-aging agent RD, and 1-2 parts of an anti-aging agent 4020. The sealing gasket can resist high temperature, has high mechanical strength, high oil resistance and good corrosion resistance, can work in acids, alkalis, oil and other media for a long time, and is durable in use.