Abstract: C₅F₁₀O gas has excellent insulation and environmental protection characteristics, and has good application prospects as an insulating dielectric in medium- and low-voltage grade electrical equipment. However, the compatibility of C₅F₁₀O/CO₂ gas mixture with ethylene-propylene-diene monomer(EPDM) sealing materials commonly used in gas insulation equipment needs to be studied before its engineering application. In this paper, the compatibility of C₅F₁₀O gas and EPDM rubber was studied by building a rubber compatibility test platform and using the method of thermally accelerated aging. After the tests, the changes in the composition of gas mixture, the mechanical properties, surface morphology and element changes of the EPDM rubber were tested. Studies have shown that, under thermal aging conditions, chemical reactions between EPDM and C₅F₁₀O gas may occur, and EPDM will react with C₅F₁₀O and C₃F₆ to reduce the C₃F₆ produced by the decomposition of C₅F₁₀O gas; however, in the meantime, the decomposition of C₅F₁₀O gas will be promoted to produce C₃F₆O and C₃HF₇. After the end of the aging test, the surface of the EPDM rubber is covered with a layer of oily substances. EPDM rubber becomes brittle and reduces its mechanical properties, and a large number of crystal particles will appear on the surface. After C₅F₁₀O gas corrodes EPDM rubber, the aging of EPDM rubber will be accelerated and its service life will be shortened. Related test results will provide references for the design and manufacturing process of C₅F₁₀O gas insulation equipment.