Abstract: Drainages can show more complex structure at the smaller scale, which is the representation of the corresponding basin's self-similarity. The detailed structures for different debris flow basins reflect their ability to transport material, which suggests that the small-scale structure plays an important role in the debris flow formation. Therefore, the paper focuses on the drainage hierarchical characteristic of debris flow basin, and two basin parameters (first-order stream number and area threshold) are used to examine this characteristic because the two are not affected by stream ordering methods and DEM errors. Three typical debris flow basins with different catchment area (Jiangjia, Longdong and Guxiang Ravine) were studied, which respectively located in three distinct regions. Using hydrological analysis tool in ArcInfo software the stream networks with different catchment area thresholds were extracted from these basins' DEM and one set of first-order subbasin was identified. It is obvious that these subbasins occupy the whole basin's fringe region where mass transportation starts. So this suggests that the subbasins play an important role in the initiation and material supply of debris flows. Another point is that the number of extracted first-order stream decreases rapidly with the area threshold increasing. It is found that the two parameters have close relation N=RA(a/m) have close relation, and exponent a equals to-1 and coefficient k only relates to the total basin area, namely for the same basin the product of first-order number with area threshold is constant in a wide scale range. The relationship may show that the ability of debris flow basin to transport material doesn't change in so wide scale range. Further research will be paid more attention to the distinction of exponent a and coefficient k between debris-flow basin and non-debris-flow basin.