Abstract:At 9:00 5th September 2004,the worst new landslide in the history of Chongqing,China since 1949 occurred in Ji′an village Wanzhou City. Seven people were killed or injured by the landslide. The landslide destroyed an important local market town,the highway and the expressway under construction,and left a thousand of people homeless. There are great losses of life and economy in the landslide. The landslide is 1 247 m long,394 m wide in average with 7.0×106 m3 in volume and 0.7 km2 in area. On the basis of field investigation and study,the geologic environment and characters of Ji′an landslide are studied in detail. According to the environment characters and occurring process of Ji′an landslide,the geologic origin and the environment origin are researched. The conclusion is that the Ji′an landslide is a new consequent rock landslide of traction type in Jurassic. The hydrogeological structure type is the crucial factor;the geological structure type is the control factor;the valley development and evolvement type is the affecting factor;and the high intense and large rainfall is the triggering factor. At last,it is suggested to strengthen the landslide triggering mechanism study and landslide monitor.