This paper is the result of oil and gas exploration engineering.
[Objective] There is a good prospect of oil and gas exploration of Juyanhai depression of Yingen-Ejin Basin, but there are some controversies on the understanding of the age of the main petrostratigraphic unit and the age of the main oil-bearing reservoir revealed by wells, so it is great significance to the evaluation and study of oil and gas geological conditions, and the exploration and deployment by systematic stratigraphic division and correlation, and define the ages of the main petrostratigraphic units and oil and gas layers for the tectonic and sedimentary evolution of the basin. [Methods] Based on the comprehensive study on the petrology, lithologic association and paleontological characteristics of wells in different sags,, the formation correlation mark established by regional formation characteristics, unconformity interface determined by seismic profile, constraints on stratigraphic age of LAICP-MS zircon U-Pb and so on, the conclusion of stratigraphic division and correlation is formed. [Results] There are two structural layers of Cretaceous and Carboniferous and Permian of wells in Juyanhai depression, the correlation marks of strata in each depression are significant, and the main oil-bearing strata are the middle-Lower Permian and Ganquan formation of Upper Carboniferous and Lower Permian. [Conclusions] Yingen-Ejin Basin is a superimposed basin of Carboniferous-Permian and Cretaceous, and the geological conditions of Carboniferous and Permian are favorable, so it should be used as the direction of oil and gas exploration.