For insulators used in high-voltage transmission systems, silicone rubber materials exposed to ultraviolet radiation for a long time will age, which deteriorates their mechanical properties and seriously threatens their safe service. Therefore, it is of great significance to study the degradation behavior of mechanical properties of silicone rubber materials under strong ultraviolet environment. This work used UV-B 313 ultraviolet lamps to artificially accelerate the aging of silicone rubber materials for 1000 h, and studied the hardness, tensile properties, tearing properties of silicone rubber materials. The results show that with the increase of aging time, the tensile strength of silicone rubber material decreases, and the rate of decrease gradually slows down. The tear strength first increases and then decreases. The hardness of silicone rubber material increases, and the rate of increase gradually slows down. This is because that UV-B radiation can cut off C-H bonds and Si-C bonds in silicone rubber, and the broken free radicals interact with each other to form cross-linked structures, increasing the molecular weight and number of stress concentration points. Therefore, the hardness is enhanced and the tensile strength attenuates. The competition between the crosslink density of silicone rubber and stress concentration points lead to fluctuation of tearing strength.