Factors controlling the depositionalevolution and sequence development of the Middle Ordovician Yijianfang Formation inthe Tarim basin are still controversial. Based on the identification of sedimentary facies and high- frequency meter- scale sedimentary cycles and their vertical stacking patterns, the Yijianfang Formation of the Lianglitage Mountain area (western Tarim basin) is systematically studied, in order to clarify the depositionalevolution and sequence development and their controls. The conclusions are as follows: ① During the deposition of the Yijianfang Formation, the Lianglitage Mountain area was represented by a carbonate ramp system, on which ten types of lithofacies and two depositional facies belts (peri- restricted and open- marine subtidal facies). ② Two types of high- frequency meter- scale sedimentary cycles were recognized, including peri- restricted and open- marine subtidal sedimentary cycles. ③ Two and half third- order depositional sequences were identified, whose boundaries were characterized by transitional lithology zones. A complete third- order depositional sequence consists of a lower transgressive part and an upper regressive one. ④ The depositionalevolution and sequence creation were primarily dictated by paleogeographic configuration, sedimentary microreliefs, relative sea- level variations of different orders. The paleogeographic configuration controlled the overall distributional patterns of depositional faciesbelts; the sedimentary microreliefs determined the preferable positions of specific lithofacies (ie, Calathium reef); relative sea- level variations of different orders governed the tempo- spatial distribution of depositional facies.