Evaluation of dangerous degree of debris flow is a complex system problem of uncertainty. For the sake of accurate evaluation of the dangerous degree of debris flow, so as to provide scientific basis for the prevention of debris flow, this paper brings forward the prediction method for dangerous degree of debris flow based on fractal dimension weight. The results are consistent with that from other method. It is shown that the model here is feasible and effective in predicting classification of evaluation of dangerous degree of debris flow. Moreover, particular score of each sample could be computed by the model. So it has more precise classification and is a rather better method.