Abstract: In the light of well logs and associated data, the Sanjianfang Formation along the Shanshan-Qiuling boundary in Xinjiang is believed to be made up of the braided delta and lacustrine deposits, especially the braided delta plain and front subfacies, which may be subdivided into 8 sedimentary microfacies. The Sanjianfang Formation has undergone several stages of evolution:progradational-regradational depositional sequences during the early stage, braided delta plain deposits during the middle stage, and braided delta front deposits during the later stage of the deposition of the Sanjianfang Formation. The detritus are mostly derived from the southeastern and southern parts, and locally from the northern part of the basin.