Abstract: This paper discusses the method for measuring the fractional dimension of hydrographic features.The fractional dimension of coastlines and rivers on the series scale topographic map is measured by using the method.The change regularity of the fractional dimension of hydrographic feature is found as fellow:1) The smaller the scale of the map is,the smaller the fractional dimension of hydrographic feature is.2) The smaller the scale of the map is,the smaller the self-similarity is.Coastlines and rivers on the map are generalized using the change regularity and fractal geometry.The result of the cartographic generalization is satisfactory.