Abstract: The most prominent feature of a strong earthquake is the long surface ruptures that cause severe faulting and seismic damage. The widely distributed active faults are the natural carriers that produce surface-rupture events. Numerous multi-disciplinary observations and simulations on the geodynamic processes of the expansion, propagation, and termination of large surface rupture event, reveal that the geometric changes of active faults have a significant influence on the development of surface ruptures. Geometrically complex zones on active faults, such as large-angle changes in strike and complex step zones, could have important impact on the propagation of surface ruptures and the distribution of fault displacements. However, previous studies on the interaction between the geometric characteristics of active faults and the underlying rock geology have been relatively limited, only confined to the observation of high-temperature and high-pressure experiments. With the development of high-resolution geographic technology and quantitative research methods on active faults, it is now possible to finely characterize the geometric structure of large-scale faults and recognize the multi-parameter displaced landform characteristics. Here, we utilized high-resolution topographic data (0.5m) from the Fodongmiao-Hongyazi Frontal Thrust (FFT) on the northeastern margin of Tibetan Plateau, spanning approximately 120km in length, to identify and compare the parameters and characteristics of the faulted landform with the underlying bedrock geology. The results revealed significant correspondences between changes in faulted landform parameters, the boundaries of fault segments, and zones of vertical separation attenuation. In the middle section of the fault, where Silurian granite is located, the geometric structure of the fault was found to be rougher, and the shallow deformation zone was wider than in the eastern and western segments. The distribution of the step width also varied more drastically along the fault. Thus, this study suggests that the bedrock geology may exert strong control over the shallow structural deformation of the thrust faults. The potential impact of underlying geology should be taken into consideration in the analysis of active fault related seismic hazards.