High temperature vulcanized (HTV) silicone rubber composite insulators are widely used in UHV transmission lines, and its ultraviolet aging resistance has been paid more and more attention. In this paper, the samples of high temperature vulcanized silicone rubber come from two manufacturers, X-ray full spectrum scanning and narrow zone spectrum analysis were carried out on the radiated samples to analyze the influence of ultraviolet radiation on the surface chemical properties of high temperature vulcanized silicone rubber, and then to determine the aging mechanism of high temperature vulcanized silicone rubber. The results are as follows: the main elements of high temperature vulcanized silicone rubber are O, C and Si, among which O1S mainly exist in the form of O—Si—O (532.4 eV). After ultraviolet radiation, the COOH peak of 534 eV was increased, and the integral area increased with the extension of irradiation time. C1S was C—H, C—C (284.8 eV) or C—O (286.3 eV). With the extension of radiation time, the integral area of C—H and C—C binding energy peak decreased, while that of C—O binding energy peak increased slightly. Si2p was Si—C (102.39 eV), the binding energy peak of SiOx (x=3～4) was increased after ultraviolet radiation (103.6 eV), and the integral area increased with the extension of radiation time. The mechanism of accelerated aging caused by UV radiation is that part of Si—C and C—C bonds with a low bond energy of silicone rubber are cut off by ultraviolet radiation. After cleavage, free radicals can combine with each other and cross-link to form SiOx (x=3～4); Free radicals are oxidized by ozone to COOH. X-ray photoelectron spectroscopy (XPS) plays an important role in the study of aging mechanism of high temperature vulcanized silicone rubber.