Abstract: The lacustrine shale of Early Cretaceous Bayingebi Formation is a suite of important source rocks resources in the Yingen-Ejin Banner basin.We studied the characteristics of the major elements, trace elements and rare earth elements, and the paleoenvironment and organic matter enrichment model of the black shale by the geochemical analysis of the Balongwula section.The results show that Sr/Ba value is 0.14~0.24, average value is 0.18, B/Ga value is 3.89~6.51, average value is 5.03, equivalent boron content is 230.88×10^-6~375.99×10^-6, average value is 294.95×10 ^-6, paleosalinity is 11.97‰~15.83‰, average value is 14.70‰; V/(V+Ni) value is 0.67~0.84, average value is 0.74, the Ce_anom value is -0.113~0.018, average value is -0.055; the paleoclimate index(C) is 0.80~1.34, average value is 1.06, the chemical index alteration(CIA) is 75~81, average value is 79; the ancient water depth is 4.16~88.04 m, average value is 33.40 m; P/Ti value is 0.10~0.22, average value is 0.15, the excess barium(Ba_XS) is -46.5×10^-6~144.5×10^-6, average value is 38.85×10^-6.Based on the characteristics of various parameters, the black shale in the study area is deposited in a warm and humid climate, with a sedimentary environment of deep lacustrine facies under an brackish water and anoxic condition.The paleoproductivity reflect a low initial paleoproductivity.The study on the correlation between organic carbon content and sedimentary environment shows that the organic matter enrichment in black shale of Bayingebi Formation is the result of the combined action of paleosalinity, oxidation-reduction conditions, paleoclimate and paleo-productivity.This will provide theoretical support for the sedimentary evolution of Mesozoic and the evaluation of oil and gas resources in Yingen-Ejin Banner Basin.