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The coal‐bearing Yan'an Formation in the Ordos Basin of the Middle Jurassic was deposited in a river delta–lacustrine sedimentary environment with relatively stable accumulation rates. Spectral analysis and wavelet transform analysis of the natural gamma‐ray (GR) curves from several boreholes through the Yan'an Formation yielded five main sedimentary cycles with wavelengths of 34–57, 10–18, 8–14, 2.9–4.1, and 2–3 m. These cycles were controlled by orbital cycles of eccentricity (405, 128, and 97 kyr), obliquity (35 kyr), and precession (22 kyr), and the long‐eccentricity period of 405 kyr was the most significant cycle. Filtering the sedimentary records for the long‐wavelength cycle and short‐wavelength cycle implies that there are 11 long‐eccentricity cycles and 35 short‐eccentricity cycles preserved in the Yan'an Formation. Assigning the 405 kyr long‐eccentricity cycle to the filtered 11 primary long‐wavelength cycles implies that the Yan'an Formation spanned 4.4 Myr. The orbital–climate cycles were critical factors in the sediment facies changes and episodes of coal formation within the basin. The long‐eccentricity cycles of the Milankovitch cycle are the predominant control factors of the coal seams deposited in the Middle Jurassic Yan'an Formation. [ABSTRACT FROM AUTHOR]

• The Milankovitch cycles are well preserved in the Dameigou Formation. • Coal seams derive organic matter from submerged and floating aquatic plants, as well as terrestrial higher plants. • Differences in the sources of organic matter in coal seams are driven by a combination of eccentricity, obliquity, and precession. Coal seams, as a terrestrial carbon sink, are not only important sedimentary and energy mineral resources but also excellent recorders of paleoclimate change. The study of coal-bearing strata is particularly significant in exploring the relationship between geological records and orbital forcing. However, the understanding of the relationship between coal seams of different sources of organic matter and astronomical cycles is incomplete. This study focuses on the Dameigou Formation, a typical Jurassic coal seam in the Qaidam Basin, Northwestern China. Organic petrology analysis, biomarker analysis, and whole-rock mineral analysis were combined to reconstruct the vegetation types and paleolake water level changes during coal seam deposition. In addition, using a time-series analysis method and high-precision gamma-scanning data from Well D1, we established a floating astronomical timescale and a time-depth model for cyclostratigraphical analysis. The results show that the Dameigou Formation, as coal-bearing strata, preserves well-developed Milankovitch cycles, and the climatic conditions and vegetation types during coal formation vary among different coal seams. Different patterns of variation in eccentricity, obliquity, and procession determine the thickness of the coal seam. This study is of great significance for understanding the astronomical factors that influenced climate evolution and coal deposition during the Middle Jurassic. [ABSTRACT FROM AUTHOR]