The Wenchuan earthquake has caused numerous landslides and avalanches as the sources for debris flows. A typical example is the Miancu Gully in Maoxian, where accumulates tremendous volume of loose solid materials that have formed 12 dammed lakes. Combining field surveys, Quickbird images (with spatial resolution of 0.61m) after the earthquake are used to identify the avalanches and landslides. Results show that there are 65 landslides and avalanches in the gully, amounting to area of 3.8×106m2. Among them there are 7 having area over 106m2. The 12 dammed lakes have a total area of 9.27×103 m2. The materials come mainly from the granite in the middle and the lower reaches, in volume of 1.56×107m3, and those from the upper reaches are shallow landslides, in volume of 1.87×106m3. Combining with metrological and loose materials sources conditions, tendency of debris flow activity is analyzed and some advices are proposed for Miancu gully debris flow countermeasure.