A set of deep-water gravity flow deposits with typical sand mud interbedding are developed in the Ordovician lashizhong formation in the western margin of the Ordos Basin, and the gravity flow complex channel in the lower part is developed.Based on outcrop measurement, statistics of channel shape parameters, collection of rock samples, combined with microscopic observation, lithofacies analysis and particle size test, this paper discusses the sedimentary characteristics, main controlling factors, evolution process and sedimentary model of complex channel.The results show that:(1) The complex channel in the study area is mainly composed of fine sand, silt and few gravel, with medium overall sorting. The lithofacies of massive bedding gravelly limestone (Cm), grain sequence bedding fine siltstone (Sg), parallel bedding fine sandstone (Sp), cross bedding siltstone (Fc) and horizontal bedding mudstone (Mh) and incomplete Bauma sequence lithofacies association are identified. The frequency accumulation curve is mostly normal single peak, the probability accumulation curve is mainly distributed in one section, and the C-M diagram shows a long strip parallel to the baseline of C = M. It shows that the complex channel in the study area has typical turbidity current sedimentary characteristics.(2)Factors such as provenance supply, sea level change and regional tectonic activity are closely related to the changes of gravity flow properties and energy, which makes the composite channel of lashizhong formation in Ordos Basin show complex multi-stage filling and evolution.(3)The complex channel in the study area has roughly experienced four evolution periods, showing four positive cycles in the vertical direction, reflecting the change process of gravity flow energy from strong to weak. The characteristics of single channel shape, lithofacies combination, grain size and channel superposition mode in each stage of channel are different.(4)During the lashizhong formation, the sea level fluctuated, and the terrigenous clastic materials from the North China platform was slowly transported and deposited from northeast to southwest down the marginal slope of the depression. Under the action of multiple turbidity current events, the complex channel sedimentary model of multi-stage erosion and filling in slope basin environment is developed.