Abstract: This paper describes the fractal characteristics of river network,the computation methods and the interpretation of the fractal dimension of the river networks.Based on the calculation of fractal dimension in fourteen large basins and sixty-seven subbasins in China the following points are pointed out in this paper;(1) The river networks are fractals.Their geometric structrures has some self-simialrity.(2) The fractal dimension of river networks can be computed by box counting method.Suitable box size should be selected before reliable result can be got.(3) The real river system is too complicated to be described by just one fractal dimension.Multi-fractals is more suitable for depicting large river systems.Because the large river basins have many subbasins.And in every subbasin,the environment is quite different and there can be calculated a dimension.(4) The fractal dimension of river network reflects the degree of the river evolution.Using the fractal dimension,we can divide the evolution stages of the cycle of erosion through which the river systems are on.The larger the fractal dimension,the later the stage.The threshold for separating the three evolution stages are:D=1.6 and D=1.89.These two values remain further improvement.