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While installing airtermination System in the Great Wall watchtowers in sections open to tourists, it is necessary to take into account fully not only the type and scope of protection, but also the lightning disturbance on the watchtowers and the influence on the overall outlook of the Great Wall. The installation method of lightning rods for direct lightning protection on the watchtowers is described. According to the lightning protection categories of the Great Wall and the principle of the rolling ball method, the lightning rod heights in four outer corners of different watchtowers are calculated, which should be controlled below 45 m to protect visitors. Simultaneously, the lightning rod heights in the watchtowers prohibiting climbing should not exceed 1 m. According to the cultural relics principle of the minimal intervention on the Great Wall when installing lightning arrester, the possibilities of reducing the number of lightning rods are discussed. It is found that when the number of lightning rods is less than four, the lightning rod height will increase significantly and obvious negative effects will be brought on the appearance, so this way should not be used. In addition, the protective measures should be taken to prevent the contact voltage where visitors may come into contact with the lightning rod parts.