Abstract: Significant discoveries of petroleum exploration have been achieved in 2017 in the Linhe Depression, Hetao Basin. Based on a literature review of the tectonic evolution of the study area since the Mesozoic, combined methods of well-seismic comparison and basin analogy, the Mesozoic tectostratigraphic units of Jilantai Sag have been determined, and their occurrence and significance have also been studied. The results show that, except for the Triassic, the Mesozoic strata were well developed in the study area. Particularly, the Cretaceous strata can be further divided into three tectostratigraphic units, i.e., K1^I、K1^II and K1
^III; The K1 ^I is characterized by abroad sedimentation unit covering the whole study area, while the other tectostratigraphic units are wedge-shaped with major axes aligning along the NNE main faults; The Mesozoic basin type of the Jilantai Sag have experienced rift stage during the Early-Middle Jurassic, rift stage during the early Early Cretaceous, transitional stage from rift to depression during the middle Early Cretaceous, depression stage during the late Early Cretaceous; The strata of the K1 ^II and K1 ^III tectostratigraphic units located between the faults F₃ and F ₇, and the Jtectostratigraphic unit located in the east of fault F ₇ show great potential of petroleum exploration.

Key words: Jilantai Sag, Mesozoic, tectostratigraphic unit, division and correlation, occurrence and significance