This paper takes the earliest established and highest-level City God Temple in Taiwan as an example, to explore how this belief can go through different eras, still retain its personality and continue. The study found that there are four reasons. First, although the Ming and Qing dynasties institutionalized the city god, officials and people still maintained their own beliefs in him, and the god never broke away from the civil society. Second, the folk belief is a cultural symbol or ideology of the empire. Even if it leaves the imperial period, the belief in the city god still retains the hierarchy of the bureaucracy, and the folk still regard the god as the administrator of the underworld and the judge of the underworld. Thirdly, city god temple will not only deliberately highlight its old titles, ranks, cultural relics, and temple regulations, but also emphasize the image, functions, and relevant efficacies of the deity, so as to strengthen the unique impression of the believers. Fourth, the temple also provides the services needed by modern believers by extending and explaining the old functions, adding worship gods with different specialties, and using the expertise and functions of the city god to serve the gods.