The Lianglitag Formation (Upper Ordovician) reef-bank complexes were formed in the high-energy belt of the platform margin along Tazhong Slopebreak I. Sedimentary units mainly include reef mound, carbonate mudmound, bioclastic bank and granule shoal. These units show as multiple re-occurrences throughout vertical assemblage. Single complex origins from basal bioclastic bank, successes as carbonate mudmound or reef mound in the upper part. Bioclastic bank overlaps the mound or reef marking a new cycle of the reef-bank complex building. Reefs are mainly distributed along the high part of the slopebreak with width from three to ten kilometers. Meanwhile, banks are more common in the inner side of the slopebreak. The magnitudes of the reefs are changeable temporally and spatially. Reef dwindles migrated gradually towards the slopebreak I from the Member 3 to the Member 1 of the Lianglitag Formation. Affected by multiple phases of diagenesis and structural fracturing, the reef-bank complexes along the platform margin are significant of reservoirs characterized by their variation in heterogeneity.