The Paleogene Niubao Formation in the Nyima Basin, Tibet, shows two main types of sediment: fan delta and lacustrine. The fan delta sediment comes from the Gaize-Selingcuo thrust block in the southern Nyima Basin. The sedimentation at Chaangba area can be divided into three cycles, each showing a transition between fan delta and lacustrine sediment. This research helps understand the uplift mechanism, ancient geography, and potential oil resources in the Qinghai-Tibet plateau.