The embodiment of the invention provides an ethylene-propylene monomer seal ring with excellent high/low-temperature properties. The seal ring is prepared from 80-100 parts of ethylene-propylene monomer, 50-75 parts of N550 carbon black, 5-10 parts of high-flash paraffin oil, 10-20 parts of nano argil, 4-8 parts of zinc oxide, 1 part of stearic acid, 2.5 parts of vulcanizing agent DCP (dicumyl peroxide), 5-10 parts of non-phthalate polyester plasticizer, 2 parts of anti-aging agent RD and 0.5 part of heat-resistant agent. The vulcanizing agent DCP and non-phthalate polyester plasticizer are added to enhance the high/low temperature resistance of the seal ring.