Abstract: Wenjia gully is located at the epicenter area of the 2008 Wenchuan Earthquake.A huge landslide was ever triggered by the earthquake.During the passed three flood seasons,at least five typical debris flows occurred at Wenjia gully.In particular,a severest debris flow occurred on Aug.13, 2010. It had a volume up to 3.1107m3.Five residents lost their lives unfortunately and hundreds of new-built houses were buried during the catastrophic event.However,it was fortunate that almost all the residents evacuated successfully before the debris flow occurred.In this paper,on the basis of tracking investigation,the mechanism and characteristics of the Wenjia-gully debris flows were discussed and some suggestions were put forward.The acknowledges obtained after investigation and analysis are as follows: (1)The debris flows were caused by both Wenchuan earthquake and strong rainfall.As the debris flow formation is concerned,a circle was presented as runoff-erosion-collapse-engulfment-erosion-collapse-enlargement-,and so on; (2)The critical rainfall initiated debris flow was significantly decreased and a power-law relation is existed between debris flow magnitude and daily rainfall,which can be used to predict the volume of debris flow on the basis of weather forecasting; (3)As the occurrence process is concerned,the debris flow lasted for a long duration and moved a far distance; (4)In terms of destroying process,a clear chain characteristic was taken on with several damage ways; (5)Debris flow magnitude was enlarged and the frequency was higher obviously.