A complete progressive and regressive cycle occurred in the early Early Carboniferous in the eastern part of the North Qilian Mountains. The relative sea level changes obviously controlled the evolution of brachiopods of the study area during this period. It seems that the stability of living environment is the foundation of that whether the process of community succession can take place for an enough long time. Among all those influencing ecological factors of community succession, the property and stability of substrate is the most important one, but the food supply, water salinity and hydrodynamics etc. also play important roles. In the vertical, the most important controlling factor of community replacement is water depth, and which is closely related to the sea-level changes in this area. In the horizontal, besides the water depth, the amount of terrigenous clastic materials, seawater circuit and its salinity also deeply influence the distribution of benthic communities. The benthic assemblage eco-positions of early Early Carboniferous brachiopod communities are between BA1 and BA2, and there is no BA3-BA5 deep-water communities in this area, this indicates that the sea water depth at this period in the study area is commonly less than 10m. Under the control of Paleogeography, the distributional area of BA2 benthic assemblage eco-positions are mainly localized around Jingtai County, and the water depth is obviously shallower westward.