Abstract: A one-time runout volume of debris flow formed after earthquake is an important index to measure the scale of debris flow and the control of debris flow in the future. Therefore, using the existing field data and taking three influencing factors into account (ditch bed roughness degree, ditch slope, rainfall intensity), the laboratory model experiment was carried out to study the law of one-time solid runout amount of Qinglin gully and its calculation model was obtained. Through verification with historical debris flow and comparison with other calculation models, it is found that this model has the features of predictability, accuracy and convenience, which can play a guiding role in disaster prevention and reduction of similar debris flows in this region.