By stratigraphic means, the paper makes division and comparison tothe geological sections from sedimentary bodies of debris flow in thelate pleistocene in Wudu, establishing synthetic geological columna sec-tions of the debris flow of this period,it also analyses the characteristicsof sedimentary facies in detail. The sedimentary bodies of debris flow inthe period are composed of mud flow facies, sheet flow facies, whichbear relationship on the action of debris flow, and alluvial facies andloess soil facies which have nothing to do with the action of the debrisflow.From this the paper deduces the forming environment of them, ex-plores the relationship among the occurence, ceasing, new tectonism andclimate of the debris flow, and then the action period of debris flow isdivided into four action phases.