This paper reports the basic unit (i.e., the sedimentary sequence is composed of fine-grained sandstone, siltstone, and shale) of Xujiajuan Formation of the Xiangshan Group, Ningxia, China. This unit is divided into a lower dense flow deposit division (Ⅰ), an intermediate traction flow deposit division (Ⅱ), and an upper suspension deposit division (Ⅲ). Our results show that: ① divisionⅠis composed of fine-grained sandstone and silty sandstone with no obvious separation of grain-size in different bed thickness; ② fine-grained sandy siltstone is very poorly developed, thus, the grain-size break between divisionⅠand divisionⅡwas occurred; ③ perfect divisionⅡincludes two series of cross beddings, one is parallel and quasi-planar and combined-flow-ripple lamination and small-scale hummocky cross stratification, the other is unidirectional and bi-directional cross lamination and parallel lamination; and ④ micrites in division Ⅲ exhibit lenticular thin bedding with irregular surface at the bottom. Compared with the previous research on turbidity currents deposition, these results suggest that: ① divisionⅠcould be the product of high density depletive flow with high suspended-fallout rate; ② divisionⅡmay be formed by the processes which is dominated by internal-waves and internal tides; ③ division Ⅲ may be formed by a complex process involving both vertical setting and slow lateral advection; and ④ the turbidity currents while depositing can be viewed as bipartite flows.