Abstract: It is one of the most important challenges to research the controlling factors and formation mechanisms of Martian gullies at impact crater walls and sequentially to explore the geological processes near the surface of Mars. In this paper, the fractal theory was used to study the gully's alcoves in different orientations of nine craters at the mid-latitudes in the southern hemisphere of Mars. The results suggest significant positive correlation between the fractal characteristics of the gullies and the maturity of their development. The fractal values of the gully's alcoves have close relation to the orientations of gullies and the poleward facing gullies have higher fractal values than those of equatorward facing gullies. The local differences of climate characteristics in different orientations of the same crater walls mainly control the existence and amount of water, which causes the differences of the maturity and fractal values of gullies in different orientations of the crater walls. The results of our research provide one of the evidences for the accumulation/melting of surface snowpacks formation model.