Abstract: Based on fractal theory, the fractal dimensions of different geomorphological regions in the Yangtze River basin are calculated, and it is found that there are significant fractal characteristics of river systems in different geomorphological regions of the Yangtze River basin. Through water system fractal dimensions, the geomorphological development stages of different geomorphological units are quantitatively determined. The results show that: ①the fractal dimension of river system in the Yangtze River basin shows an increasing trend from west to east with three-step distribution. ②the density of river network, an index to judge the degree of drainage system density, is positively correlated with the fractal dimension of river network. ③the development stages of different geomorphological regions in all of the Yangtze River basin are at the age of infancy, except the Nanyang basin, but there are still significant differences in development degree among different geomorphological regions. ④ the river system complexity and the degree of erosion development are significantly diversified in the low-middle mountains and plains of the middle and lower Yangtze River because of urbanization and human activities.