Abstract: Using the data of outcrop, drilling, laboratory analysis and seismic, the paper compares the sedimentary textures and reef-flat reservoirs of 3 sets of platform margin zones developed on the east and west sides of Kaijiang—Liangping continental shelf and the west side of Chengkou—Exi trough during the Changxing Period of the Late Permian in the northeastern Sichuan basin, and identifies 2 sedimentary textures of migration-aggradation type and aggradation type. The platform margin zone of migration-aggradation type mainly consists of 2 platform margin zones of Yuanba—Longgang—Xinglongchang and Zhenba—Chengkou—Lichuan, the biological reef flat has an obvious steep-gentle alternating structure, the platform margin slope and reef flat in the gentle slope area are characterized by significantly migration and wide distribution, and obvious aggradation occurs in the steep slope area. The platform margin zone of aggradation type is dominated by the platform margin zone of Tiechanghe—Puguang—Luojiazhai, in which the geomorphology is different laterally, and platform margin reef flats are developed concentratedly and have no obvious migration. Both the palaeogeomorphology and sea level changes during deposition controlled the development of platform margin reef flat and the overall reservoir distribution. Biological reef flat is mainly distributed in the middle—upper parts of highstand system tract, dolomite reservoir was generally developed at the late HST period and the thickness of the dolomite reservoir in the steep slope area is larger than that in the gentle slope area. The reservoir distribution is featured with obvious vertical difference and segmentation. The dolomite reservoir tends to form in the platform margin zone of aggradation type in the first member of Changxing formation and slightly strong dolomitization is noted in the steep slope area. Contiguous dolomite reservoir tends to form in the migration-aggradational platform margin zone in which multiple rows of biological reef flat co-exist in the second member of Changxing formation, and relatively narrow dolomitized belts are distributed in the aggradational platform margin reef flat