The 8th member of Shihezi Formation in Block Su6 of Sulige gas field is the main gas-producing strata of the Sulige gas field in the Ordos Basin. However，the understandings on the sedimentary characteristics have long been controversial and the cognition for evolution of sandbodies have remained unclear. Based on the data of rock lithology，sedimentary architecture，cycle characteristics and other sedimentary facies indicators，the 8th member of Shihezi Formation in Block Su6 belongs to the fluvial sedimentary facie. Furthermore，works have been made to that the lower 8th member of Shihezi Formation is the braided river facies in which microfacies of central bar，braided channel，floodplain and overbank develop；while the upper 8th member is the meandering river facies in which marginal bar，abandoned channel，floodplain and overbank develop. According to the characteristics of multistage positive cycle of natural gamma logging curve and the difference in incision degree，the positive cycle superposition in the target layer of the study area can be subdivided into 4 types：aggradation superposition-strong incision，aggradation superposition-medium incision，retrogradation superposition-medium incision and retrogradation superposition-poor incision. According to the difference of positive cycle characteristics and a comparison method based on cyclic and hierarchical control，the lower 8th member can be subdivided into 2 sets of subzone and 6 sets of single layer from bottom to up，while the upper 8th member can be subdivided into 2 sets of subzone and 4 sets of single layer. On this basis，through the identification of single channel and the extraction of channel architecture elements，the evolutionary process of channel sand body in the study area was divided into 10 periods and 4 stages. The 1st，2nd and 3rd periods mark the evolution of the pebbly braided river；the 4th，5th and 6th periods indicate the evolution of the sandy braided channel；the 7th and 8th periods correspond to the evolution of the pebbly meandering channel，and the 9th and 10th periods are characterized by the evolution of sandy meandering channel.