Abstract: The Y-9 reservoir is the main production layer in Dayangwan area of Jingbian Oilfield. Taking the sedimentary system, low-amplitude structure and paleogeomorphology as an organic whole, the paper focuses on the controlling factors of reservoir. The results show that the paleogeomorphology controls the distribution of sedimentary facies and formation of low-amplitude structure of Y-9 reservoir, and also the distribution of reservoir through the favorable accumulation disposition with low-amplitude structure and sedimentary sand bodies.