In the Permian Lucaogou Formation in the Jimsar Sag, lake and delta facies strata deposited, and rocks mainly include mudstone, carbonate and fine-grained clastic rock. Two tight oil cookies developed. The lower cookies are mainly in fine-grained clastic rocks, and generate in the microfacies of delta front distal bar and sheet sand. The upper cookies are mainly in crabonate rocks, and generate in the microfacies of beach bar of shore shallow lake. The upper and lower cookies are thick and widespread, indicating giant potential for tight oil reservoir.