A large number of geological disasters such as landslides, collapses and debris flows had been triggered by Wenchuan earthquake. The Hejiagou rock landslide located in Sichuan Province of China had been revealed as a typical high-speed rock landslide in May 2009. Analysis based on detailed filed survey demonstrates that the landslide which total volume is 200 × 103 m3 is composed of deluvium, residual deposit and intensive weathered bedrock (Ningqiang Formation of Siluric), and the sliding surface is located between intensive and moderate weathered bedrock. The formation process of the Hejiagou rock landslide has been identified through analysis of geological characteristics associated with kinetic process. First, the landslide composed of Quaternary deposits and intensive weathered bedrock had been upcasted and loosed by earthquake effect. After the mass had been thrown out by earthquake effect and gravity, the landslide slipped with high speed and finally accumulated at the export of the Hejiagou gully.