Abstract: The hydrological analysis tool and data management tool of ArcGIS were used to quantitatively analyze the structural characteristics of the water system of the Malizhai River Basin in the core area of Hani terrace; The fractal dimension of the water system is calculated by the grid method and Horton theory. The comparison analysis shows that the threshold value of 400 is the most consistent with the actual situation. The results show that the river network density in the Malizhai River Basin is larger as a whole and decreases with the flow direction. The development of large and small rivers is obviously different, and the water network is well developed; The fractal dimensions were all within 1.6<D≤1.89, the basin was in the prime period of geomorphologic erosion development, and developed towards the old age, the downstream erosion gradually weakened, and the lateral erosion became the main erosion type.