Abstract: To identify the formation age of Yaoshan Formation is the key to carry out stratigraphic division and correlation, to reconstruct prototype basin and to evaluate regional resources in west margin of Ordos basin. With the development of sedimentation, the temperature of Yaoshan Formation increased gradually with the increase of the buried depth. The fission track thermal history simulation result of sandstone samples from Yaoshanzu Formation in Tanshan demonstrates that the initial burial warming time was 196 Ma and the burial warming time was between 196 Ma and 168 Ma. It shows Yaoshan Formation was deposited between 196 and 168 Ma in early-middle Jurassic.