Abstract: In order to study the sedimentary characteristics and to classify the architecture of braided channel sand body in Badaowan formation of Aerqingou section in the southern margin of Junggar basin, and guided by theories of sedimentology and reservoir architecture, field outcrop observation and measurement are conducted. In the sand bodies of Badaowan formation, 11 lithofacies are found, boundaries with 6 levels are classified and 4 key elements of architecture are identified on Aerqingou section, based on which a reservoir architecture development model and its distribution patterns are established for the outcrop. The results show that the sand body results from depositional superimposition of 2 stages of braided channel events; 3-level to 6-level boundaries within the sand body can reduce horizontal and vertical connectivities in different extent and increase reservoir heterogeneity. Enhanced outcrop study and using architectural methods to dissect reservoirs can help us better understand reservoir heterogeneity