Under earthquake action, complex interactions occur between urban building groups and the underlying site, known as the site-city interaction (SCI) effect. How the SCI effect influences the dynamic response characteristics of ground fissure sites remains unclear. Therefore, taking the Xi'an ground fissure as the research background, a series of numerical models were established considering frame structures with different foundation types, natural frequencies, and building densities to investigate the SCI effect on the dynamic response of ground fissure sites. The results indicate that the SCI effect reduces both the site response and the influence range of the ground fissure. When the natural frequency of the building structures matches that of the ground fissure site, the SCI effect markedly reduces the site response. When the natural frequency of the buildings matches the predominant frequency of the seismic waves, the response at some measurement points on the ground fissure site increases. However, owing to the SCI effect, the average response of the entire site still decreases. Therefore, in urban construction, the avoidance distance for ground fissures can be appropriately reduced, while resonance phenomena should be avoided as much as possible.