Abstract:All kinds of trace elements in sedimentary rocks have great flexibility and sensitivity in determining the environment and evolution process of sedimentary rocks, which is an effective parameter to record the evolution process of sedimentary rocks. Yanghugou formation in the western margin of Ordos Basin is a new type of stratigraphic system of Upper Carboniferous oil and gas with large thickness and high content of organic matter. The paleo water environment and paleoclimate are of great significance for the restoration of the sedimentary pattern and reservoir forming ability of yanghugou formation in this region. Trace elements of 47 mudstone samples from different horizons of yanghugou formation in the western margin of Ordos Basin were tested. Elements sensitive to sedimentary environment of mudstone were selected as evaluation and discrimination indicators, such as Sr, Ba, U, Th, V, Ni, Co, etc Ancient water depth and paleoclimate characteristics. The results show that: the values of Li, Sr, Ni, Ga and Sr / Ba indicate that the study area is in a freshwater brackish water environment, and occasionally saline water is injected; the values of δU, U / Th, V / (V + Ni), V / Cr and Ni / Co indicate that the study area is in a weak redox oxidation environment, and some deep water areas may have a redox environment; According to sedimentological indicators and trace fossils, the sedimentary period of yanghugou formation was dominated by shallow water environment; Sr/Cu and CaO / (MgO × Al2O3) values indicate that the study area was in a hot and dry climate in the north and central, and a warm and humid climate in the South during the yanghugou formation.