Abstract: Landsliding is a physical process involving sliding friction between its slip zone and the moved materials. It has been believed that there is a frictional heat within the slip zone when a rapid, large-scale and deep-seated landslide occurs. Illite is one of the clay minerals most sensitive to temperature that alters illite's crystallinity, and the latter has been widely used as a useful indicator of degree of metamorphism, neotectonic movement, etc. Illite crystallinity was hence used in this paper to be an indicator about a rapid, large-scale and deep-seated landslide's sliding mechanism in terms of fractional heat. By comparison of variation of indices of illite crystallinity of three landslides’ materials, i.e., the landslides at Huangtupo,Tanping and Xietan in the Three Gorges area, it was found that No. 1 slide at Huangtupo landslide, Tanping landslide and Xietan landslide were slow-moving landslides, whereas No.2 slide of Huangtupo landslide may have experienced a rapid sliding process.