TThe evolution law and development trend of secondary debris flow disaster in the strong earthquake area were significantly affected by the “post-effect”of the earthquake. The peak discharge had increased several times compared with before the earthquake, and the scale of the debris flow had increased obviously. According to the norms, the new challenge to the targeted design of prevention and control the gully debris flow in earthquake area is being put forward. Therefore, based on the case of debris flow in Wenchuan earthquake area, the factor regression analysis was used to study the intrinsic relationship between the basin characteristic parameters and the peak discharge in this paper, and a multivariate prediction model for peak discharge of debris flow was established. The problem of information superposition caused by the collinearity of the original variables was solved, the goodness of model fitting was , and the prediction accuracy was improved significantly; At last, the prediction model was used to predict the peak discharge thresholds of 32 debris flow in the study area, and the distribution law of dynamic characteristics and the scale evolution characteristics of debris flow were analyzed in strong earthquake area. Based on this, the characteristic parameters of "super-large-scale high-level long-distance debris flow" was defined, which can provide theoretical support for the design of debris flow disaster prevention and mitigation engineering in earthquake area.