The existence of rock fragments is one important features of purple soil. However, the variation in rock fragments on purple soil-mantled hillslope is poorly understood. In order to understand the spatial distribution pattern of rock fragments in purple soil, a typical catena which contained both a relatively steep slope and a relatively gentle one was selected. Ten pedons from pits dug on hillslope from crest to foot were selected and the content and size of rock fragments of soil layers varied in depth at different position of hillslope were investigated. Results show that: (1) the rock fragment content of purple soil varied in 0.4%~50%. The content of rock fragments were divided into five grades of <5% (low), 5%～10% (medium-low), 10%～20% (medium), 20%～40% (medium-high) and >40% (high). The content of rock fragments concentrated in low, medium-low, medium and medium-high grade. The small rock fragments with diameter of 5~20 mm and medium rock fragments with diameter of 20~76 mm were the main components. (2) With increasing depth of soil layer, the distance between soil layer and parent material horizon become shortening and the influence of parent material horizon on soil’s properties would increase. The contents of medium rock fragments and big rock fragments (76~250 mm) increased and the content of small rock fragments didn’t change significantly. Thus the total content of rock fragments increased as soil layer deepened. The equivalent diameter of rock fragments depended on rock fragment content ratio (content of rock fragments with different diameter divided by total rock fragment content). The relationship between equivalent diameter of rock fragments and content ratio of big rock fragments was positive very significantly, while the relationship between equivalent diameter of rock fragments and content ratio of small rock fragments was negative significantly, and there was no significant relationship between equivalent diameter of rock fragments and content ratio of medium rock fragments. With increasing depth of soil layer, the content ratio of big rock fragments increased and the content ratio of small rock fragment decreased, thus the equivalent diameter of rock fragment enlarged as soil layer deepened. (3) On the relatively steep slope, the rock fragments, especially the bigger rock fragments, rolled or crept down under the action of gravity because of the steeper slope, thus the content and equivalent diameter of rock fragments increased from crest to foot. On the relatively gentle slope, the efficiency of gravity pulling down rock fragments was induced while sorting impact of erosion was strengthened because of the gentler slope: fine earth was moved down and coarse materials was stayed in situ under the action of runoff scouring and raindrop splash. The content and equivalent diameter decreased from crest to foot. We can concluded that vertical distribution of rock fragments within soil column was determined by pedogenic process and the depth of soil layer significantly influence rock fragment content, rock fragment size and content ratio of rock fragments with different diameter, while slope-scale variation of rock fragments depended on dominant hillslope transport process, i.e. water erosion processes or gravity erosion process.