By the observation and description of field geological profiles and cores, sand is divided into four members in the Lower Ganchaigou Formation (E¹₃) in the Hongliuquan area of the Qaidam basin. This paper analyzes the sand members I and Ⅱ. Through integrating sedimentary microfacies of the profile as well as content and distribution of the microfacies sandstone, ichnographies of the sedimentary microfacies in the area are protracted. Based on the analysis of electrical characteristics of the sedimentary facies, the pattern recognition of the sedimentary microfacies and the analysis of single-well facies, the sedimentary succession and the model of sedimentary evolution are established. The results show that subaqueous channel sandbodies and sheet sandbodies of deltafront are well developed in the sand members I and Ⅱof the Lower Ganchaigou Formation. Through the study of sedimentary microfacies and evolution, favorable reservoir facies are found in the area, consequently providing a geological foundation for progressive exploration in the oilfield.