Abstract: The Babei Sag is a secondary tectonic unit in the north of Suhongtu Depression in Yingen-Ejinaqi Basin(or Yin'E Basin). Based on the sporopollen assemblages and U-Pb isotope tests of clastic zircons of the Maihanhada Formation, the stratigraphic age and provenance direction are studied. The characteristics of sporopollen assemblages show that except for the types existing in the Late Paleozoic and Mesozoic, the types appearing only in the Cretaceous are not found, and most of the types appearing in the Late Paleozoic and Triassic. The CL image and Th/U(>0.4)of zircons in the clastic rocks of the Maihanhada Formation in the Northern Suhongtu depression, Yin-E basin, indicate that most of them belong to the zircons of magma, and the age distribution of zircons is between 246Ma and 1010Ma, the concentrated distribution is the 246~390Ma, 400~560Ma. The youngest peak is 260Ma. The geological age of the Maihanhada Formation should be Permian. And the age distributions of the magmatic rocks in the area of the dagger and the Bayannuoer-Langshan-Yinshan are similar, so the two are the possible sedimentary material sources of the Maihanhada Formation.