In order to explore the relationship between geochemical characteristics and coal-forming environment of Jurassic Yan 'an period coal seam, this paper studies and analyzes the core coal samples of Daliuta mining area, and obtains the results of industrial analysis, elemental analysis and coal ash macroelements of Yan 'an Formation coal seam. According to the indexes of carbon-nitrogen ratio ( C/N ), mirror / inert ratio ( V/I ), chemical weathering index ( CIA ), ash index ( K ), m, n and c values of coal samples, the coal-forming environment was studied and identified. The results show that the main coal seam of Yan ' an Formation is low rank bituminous coal with medium-low moisture, extra-low ash, medium-high volatile and extra-low sulfur. The source of coal plants identified by C/N ratio was mainly gymnosperms developed in humid climate. The ratio of vitrinite / inertinite ( V/I ) indicates that the peat swamp is a humid climate with weak overlying water environment. The paleoclimate of the Yan 'an Formation is warm and humid during the sedimentary period of the Yan 'an Formation, and the paleo-water body is relatively stable. It is a fresh water environment of brackish water phase, and the sedimentary conditions are relatively stable. The coal-bearing strata mainly develop a lake delta sedimentary system, which is a sedimentary environment conducive to the accumulation and evolution of coal.