Abstract: Coherence functions are often used to express the similarity of ground motions at adjacent locations, and can be used to analyze the seismic responses of large structures and long structures. Coherence studies are highly dependent on site conditions. In this paper, we analyze the effects of average shear wave velocity, coefficient of variation and epicenter distance on the lagged coherence attenuation based on ground motions records form the dense arrays in the Chenghai Fault Zone. The intra- and inter-regional coherence variation were analyzed by zoning according to the site shear wave velocity; the attenuation patterns of lagged coherence under different distance groups were studied according to the epicenter distance. The study shows that the average shear velocity and the coefficient of variation of the field have effects on the attenuation of coherence. Greater average shear velocity leads to greater coherence, and larger coefficient of variation leads to faster coherence decays. When ground motion propagates between regions with different shear velocity, greater difference of shear velocity between regions leads to smaller coherence. The epicenter distance has an effect on the coherence variation. As the epicenter distance increases, the coherence increases at low frequencies and decreases at high frequencies; this effect gradually decreases as the epicenter distance increases and the "saturation" phenomenon occurs. Based on the above results, the fitting analysis of common engineering models is carried out, and the model parameters are updated, which can provide a reference for the establishment of the coherent function model considering the site variability.