Abstract: It is insufficient to reveal the morphological characteristics of rill development only by using fractal theory. Geomorphologic comentropy should also be introduced to reflect the developmental stages of rill. Combining the fractal theory with geomorphologic comentropy, we studied systematically the relationship between fractal structure of rill network, geomorphologic comentropy and the rill morphology evolution. Case analysis shows that the complexity of the rill network can be quantified accurately by rill fractal dimension, but its relationship with erosion amount is unsatisfactory. The geomorphologic comentropy is highly correlated with erosion amount, and can be used as an important parameter in the analysis of slope morphological system.