Abstract: The organic content in silicone rubber reflects not only the aging state of composite insulators, but also the quality of their products. The determination of the organic content is important for the quality monitoring of composite insulators before operation and maintenance as well as before entering the network; however, there is a lack of an efficient and accurate in-situ means to detect the organic content of silicone rubber composite insulators. Consequently, we investigated the spectral characterization of organic content in silicone rubber based on laser-induced breakdown spectroscopy. The linear calibration models of Al and Si atomic intensities, plasma temperature and Si ion atomic intensity ratio with silicone rubber organic content were established for 11 different formulations of high-temperature vulcanized silicone rubber samples, where the best goodness-of-fit was 0.9114 for plasma temperature and 0.4857 for SiⅠ390.55 nm. Finally, AlⅠ394.40 nm, AlⅠ396.15 nm, and SiⅠ390.55 nm spectral line intensities were selected as independent variables to establish a multivariate linear calibration model for the organic content, and the prediction results had a goodness-of-fit of 0.9884.