In order to strengthen the landslide prevention and control in the southeastern mountainous area of Zhejiang Province, this paper discusses the material structure and motion characteristics of Shanwai and Nanchong high speed landslides. Then it summarizes the formation causes, hazarding causes and affecting ways of the high-speed landslide in the area. Steep original terrain with artificial cut slopes, super typhoon caused rainfall and peak residual of poor strength constitute the formation causes. The high speed and distance are the main hazarding causes. The affecting ways include piling-burying, toss-impacting and airsurge-lifting.