The steep- channel debris flow is special type of debris flow in the Wenchuan earthquake zone characterized by a large quantity of source material, intense and large scale erosion thereby increasing the difficulty of geological disaster management in the earthquake area. This study analyzes the development conditions and characteristics of the steepchannel debris flow in the Futang gully and experimentally reproduces them to analyze the starting characteristics of steepchannel debris flow. The results show that under the test conditions of the slope of 20°, 25°, 30° and the runoff of 480mL/s, 410mL/s and 360mL/s, the debris flow begins in different ways (trench bed erosion type, landslide fluidization starting type, fire pipe starting type). Simultaneously, by combining the study of the variation characteristics of pore water pressure and volume moisture content in the soil during the experiment, the whole process of debris flow onset was reviewed in detail. The analysis of the test data show that the soil properties vary under different starting modes: ①the starting pore water pressure of debris flow under different test conditions shows a systematic difference, i.e. the larger the slope and runoff from the source, smaller the driving force required by the debris flow; ②larger the slope, longer the water saturation time required by the soil. At the same slope, greater the flow rate, shorter is the prewater saturation time; ③the outbreak time of debris flow is inversely proportional to the slope of gully bed, and larger the runoff, longer the duration of debris flow. Based on the experimental results, the starting velocity of debris flow calculated by the similarity theory is consistent with the field situation demonstrating that the conclusions of this study can provide a framework for the study of the rapid and steep channel debris flow in the Wenchuan earthquake area.