In order to obtain the aging mechanism of a certain kind of sealing fluororubber under high-low temperature cyclic conditions,the fluororubber seal ring was subjected to an accelerated aging test of high-low temperature conditions in oil medium.The changes of compression set,mechanical properties,microstructure, molecular structure and dynamic mechanical properties under the condition of temperature-changing oil medium were studied.The dissociation energy of several important chemical bonds of fluororubber molecules was calculated. The test results show that the maximum tensile strength and elongation at break of special fluororubber decrease with the increase of the number of cycles,and the compression set rate of fluororubber samples stored in oil medium increases gradually in the early stage of aging.The compression set rate of fluororubber samples slightly restored in the late stage of aging,as the aging time increases,the side groups of the fluororubber molecules decompose and the main chain flexibility increases.