Based on the comprehensive interpretation of geological maps, remote sensing images and digital elevation models, detailed investigations of multiple faults in the southern part of Longmen Mountain along the Qingyi River valley were conducted. The large-scale unconformity boundary of the Pre-Quaternary is used as the distribution range of faults. In addition, the latest active fault locations are determined by morphological indicators, such as faulted ridges, fault troughs, and river channel displacement. During the interpretation process, previous research results were also taken into consideration, such as the location trenches and seismic profile data. The survey results show that the Zhonggang fault and Yongfu fault developed in the contact zone between Songpan-Ganzi fold belt and Longmen Shan, and its Late Quaternary activity characteristics are not obvious. The three main faults, hinterland fault, central fault, and forland fault in the northern Longmen Shan correspond to the Gengda-Longdong fault, Yanjing-Wulong fault, and Shuangshi-Dachuan fault in the southern Longmen Shan. It shows the southern Longmen Shan has similar block structures to the northern Lonmen Shan. The three faults in the southern Longmen Shan have obvious fault geomorphic features. A difference between the southern and northern Longmen Shan is that the southern segment has many fault branches. One branch of the Yanjing-Wulong fault is the Baoxing fault, and the other one of the Shuangshi-Dachuan fault is the Xiaoguanzi fault. In the foreland area, the deep thrust extends to the shallow layers, and becomes shallow branch faults such as the Shiyang fault and Xinkaidian fault. Based on these fault distribution patterns, fault geomorphological features, and measured geological sections, it is found that the southern Longmen Shan has pure compression characteristics. The latest tectonic activity began to transform the foreland area, which is an extended thrust belt boundary. The northern section of the Longmen Shan has a lateral strike-slip component comparable to that of the thrust, indicating that during the pushing process of Tibetan Plateau, the northern edge of the Longmen Mountain slipped and escaped towards western Qinling Mountains. However, the southern Longmen Shan has a pure compressing characteristic. We consider the squeezing effect of the Songpan?Ganzi block concentrates in the arc structure in the middle of Longmen Shan belt. The arc structure controls the structural differences between the north and south of the Longmen Shan fault belt zone.