Abstract: The characteristics and formation conditions of Maliu gully debris flow were analyzed by field investigation in Longchi, Dujiangyan, Sichuan Province. The storage capacity of loosening solid matter was calculated and the range of danger zone in this area was designated. The results show that the topographic characteristics of Maliu gully basin provided favorable terrain conditions for the debris flow; besides, the Wenchuan earthquake and the Lushan earthquake have provided rich source conditions, and many heavy rainfall events have offered adequate water conditions for the formation of the debris flow. Moreover, the calculations show that the storage capacity of loosening solid matter is about 29.21×10⁴ m³ in Maliu gully, with about 13.19×10⁴ m³ in formation area, 3.27×10⁴ m³ in flowing area, 12.75×10⁴ m³ in accumulation area. In addition, the maximal hazard zone range of debris flow is 0.2471 km².