Abstract：The April 20, 2013 Lushan MW6.7 earthquake occurred in the southern Longmen Shan (LMS) causing heavy casualties and property damage. After this event, whether its causative fault is a high-angle or low-angle one, and the characteristics, attributes, and the seismotectonic model of this earthquake remain debated. In this study, three high-resolution artificial seismic reflection profiles were combined with near-surface geological data and well drilling data to interpret the shallow sedimentation and tectonic deformation of the Lushan earthquake area. We also integrated the focal mechanism solutions, earthquake relocation, and a recent deep seismic reflection profile, in combination with the tectonic evolution since Paleozoic, to analyze the geology of the southern LMS. The results suggest that three major detachments control the tectonic deformation of the upper crust in the LMS and western Sichuan Basin (SB), resulting in multiple superimposed deformation events. The coseismic active fault dips to the northwest at approximately 45°~50° at depths of 20 km, forming a Y-shaped structure. Seismic interpretations suggest that the seismogenic fault of the Lushan earthquake is a typical basement blind fault that does not penetrate into the overlying Mesozoic and Cenozoic units, and is not the Shuangshi-Dachuan fault (F4) or the frontal Dayi buried fault (F6). Deep seismic data illustrate the syndepositional characteristics of the seismogenic fault. Our study further demonstrates that the seismogenic slip occurred on a reactivated pre-existing normal fault older than Triassic age that triggered earthquakes during the Late Cenozoic. The 2013 Lushan earthquake was not a characteristic earthquake, and the structure of the Lushan earthquake zone conforms to the simple-shear fault-bend fold. Since the Late Cenozoic, with the strong and on-going compression of the Tibetan Plateau to the Sichuan Basin, the early-period normal faults were reactivated after inversion and triggered the Lushan earthquakes. These concealed and reactivated faults increase the potential risk of major earthquakes in the Longmen Shan and the western Sichuan Basin.