Abstract: There are regional faults in the Yanzi gully basin, adverse geological phenomena development, such as debris flow, landslides and collapse, which debris flow is more serious. There have been many serious debris flow disasters in history, inflicted major economic losses. On the basis of Engineering Surveying and mapping, analyzed the characteristics of debris flow source in the study area, to evaluate the loose material distribution and stability assessment of Yanzi gully, estimated the loose material total reserves. In order to predict the occurrence of debris flow when the maximum amount of the material may be out of there, Combined with the study area topography, hydrology and meteorology, lithology, geological structure and physical address phenomenon, qalitative assessment and investigation, egineering geological problems dangerous zoning were carried out of Yanzi gully.