The field survey regarding large-scale landslide (Scale) of whole Minjiang River shows that Diexi region, located in upper reach of Minjiang River, is an obvious large-scale landslide concentration area. There are 21 large-scale landslides in Diexi region, and 70% landslides belong to super large-scale landslides (Scale), as shown in Figure 1. All these landslides both blocked rivers and some barrier lakes still exist. Based on field investigations, the failure mechanism and geological environment are discussed in this study. For failure mechanism, three fracture planes cut the rock mass into separation; the stepped fractures forms slip surfaces; finally, these unstable rock mass slide. For geological environment, Diexi region is in west boundary of Minshan block, and in the N-S seismic belt and the Jiaochang arc tectonic belt, two active fractures (Songpinggou fracture and Minjiang fracture) confluence at Diexi region; all these make Diexi region be a Knick point of Minjiang River, a compression and torsion zone and a high stress concentration zone. Intensive uplift and quick incision (1.88 mm/yr.) since the middle Pleistocene formed a gorge with sharp slopes and strong lateral uploading. For failure cause, the intensive tectonic activities make the rock mass produce many fractures, numerous strong earthquakes weaken the rock mass integrity further; finally, the strong earthquake triggered them.