Abstract: Huangyang gully is located in Longchi town of Dujiangyan city, a severe disaster area of Wenchuan earthquake in Sichuan province. The earthquake induced large scale collapses and landslides which provided plenty of loose solid material for debris flow. The debris flow activity was very active after earthquake. Under the effect of heavy rainfall, debris flow occurred in the Huangyang gully both on August 13 and August 18 of 2010 as well as on July 9 of 2013, which has caused serious economic losses. Based on the field investigation of debris flow disaster, this paper presented a detailed analysis of the formation conditions and development characteristics of the debris flow, and discussed the effectiveness of debris flow prevention projects. For the problems of prevention projects and the characteristics of debris flow, following measures has been put forward by the authors: building drainage ditches in the downstream and accumulation region of debris flow to make the debris flow into Longxi river smoothly; and taking engineering and biological measures to stabilize landslides accumulation body and unstable slopes; besides, the road in the exit position of debris flow should adopt viaduct across the debris flow fan. The study results could provide a reference for the prevention and control of debris flow disaster in strong earthquake area.