Abstract: Doushantuo Formation is one of the important shale gas exploration target formations in the west Hubei of China. In view of the weak research on the paleo-environment of this formation, the paleo-environmental evolution law of the Doushantuo Formation in the Yichang Area of the west Hubei was analyzed through the collection of core samples for the testing of TOC, major elements and trace elements, and the favourable formations for the enrichment of the Doushantuo Formation were clarified. The study shows that the Member 1 and Member 3 of Doushantuo Formation are of organic-lean strata, and the Member 2 and Member 4 are of organic-rich strata, in which the Member 2 is significantly enriched in Ca, Mg, P, Ba, Sr, Zn, U, Mo, and Cu, and the Member 4 is significantly enriched in Ca, Si, P, Mo, U, Ba, and V. Member 1 and Member 3 have dry climate, high salinity, mainly oxidizing environment, and low paleoproductivity; the Member 2 has alternating warm-wet and dry-hot climate, high salinity, and frequent alternation between oxidizing and oxygen-poor environment; and the Member 4 has warm-wet climate, low salinity, and oxygen-deficient environment. Doushantuo Formation has weak paleohydraulic forces which was deposited in a strong euxinic basin, and Member 2 and Member 4 have higher paleoproductivity. Favorable block is located in the deep-water inter-platform basin at the west of Yichang City, the middle of Member 2 is a shale gas-rich favorable formation, in which the thickness of organic-rich strata with TOC>2.00% is more than 20 m, deposited in an oxygen-poor and oxygen-deficient environment, with the highest paleoproductivity, and it is the geological "sweet spot" of Doushantuo Formation shale gas exploration. The study results provide geochemical basis for the shale gas exploration of Doushantuo Formation in west Hubei of China.

Key words: paleo-environment, geochemistry, sedimentary evolution, Doushantuo Formation, west Hubei of China