The earth forest is a geomorphic type of the running water found in recent years in China. At some distribution regions of loose or semicemented fluviolacustrine facies strata, owing to scouring of rainstorm runoff, thousands of gullies and ravines and some stretches of earth columns were formed, like a stretch of forest observed at a distance, thus it was named earth forest.The earth forest landform developed the most typically in the Yuanmou Basin, Yunnan Province. Through the study, such as strata of fluviolacustrine facies, neotectonics, geomorphics, soil, climate, vegetation, etc., the authors pointed out the condition for forming the earth forest landform and its five development stages, and then divided it into four types: thin gully-earth gemma type, round basin-earth column type, broad gully column fort type and slope-remaining column type.