Silicone　rubber　insulators　always　work　at　high　altitude　regions　with　strong　UV　-B　radiation,　which　degrades　the　silicone　rubber　materials　and　threatens　the　safe　operation　of　insulators.　Therefore,　this　study　conducted　a　5OOh　UV-B　accelerated　aging　test　to　investigate　the　impact　of　UV　-　B　irradiation　on　the　silicone　rubber　materials.　The　results　indicate　that　with　the　prolongation　of　aging　time,　on　the　surface　of　silicone　rubber　material,　the　C-H　bond　content　decreases　first　and　then　increases　due　to　competitive　relationship　between　C-H　breakage　reactions　and　hydrogen　abstraction　reactions,　while　the　Si-O-Si　bond　content　increases　due　to　silanol　dehydration　condensation　reaction.　The　surface　becomes　rough　and　the　particles　are　more　obvious.　On　the　other　hand,　as　the　irradiation　depth　increased,　the　C-H　bond　content　of　the　silicone　rubber　material　decreased　owing　to　hydrogen　abstraction　reactions.　The　closer　it　was　to　the　irradiation　surface,　the　rougher　the　cross-section　is.　These　results　demonstrate　that　degradation　behaviors　of　silicone　rubber　under　UV-B　radiation　is　gradient,　which　is　important　for　operation　state　detection　and　assessment　for　outdoor　insulators.　©　2024　IEEE.