Abstract: Abundant oil shale resources are hosted in the seventh member (Chang 7) of Triassic Yanchang Formation in the southeastern Ordos Basin. However, the previous studies mainly focused on the characteristics and generation environment of oil shale. However the enrichment regularities and controlling factors of oil shale were not clear, which restricted mining and subsequent production. A sequence stratigraphic framework was established based on the comprehensive analyses of outcrops, cores and fossil specimen to determine the sedimentary environment of Chang 7 oil shale. The controlling factors of oil shale distribution were discussed by the comprehensive analysis of sedimentary facies, organic matter sources and deposition rates. The Chang 7 oil shale in the southeastern Ordos Basin was deposited in delta and lacustrine sedimentary environment. Organic geochemical analyses showed that the organic matter in the Chang 7 oil shale originated from both terrestrial and lacustrine plants. The terrestrial organic matter was probably transported to deep lakes by gravity flows. Sedimentary facies analysis and Th/U value showed that during lake expansions, water depth increasing and associated accommodation space increasing in the transgressive system tract (TST) (Chang 7₃) provided a favorable environment for organic matter enrichment. However, during the late TST, the terrestrial organic matter input was lack and the organic matter was degraded in deep lakes, which led to oil yield decreasing. Additionally, hydrocarbon migrations to adjacent turbidites also led to oil yield decreasing. (La/Yb)_N analysis showed that sedimentary environments and deposition rates controlled the spatial distribution of oil shale. In the deep lake close to delta-turbidite fan deposition systems, terrestrial and lacustrine organic matter inputs were bounteous and the deposition rate was moderate, which were beneficial to organic matter input and preservation, and provided a favorable environment for oil shale formation. In the area where delta-turbidite fan deposition systems developed, high deposition rates led to organic matter dilution, which was not beneficial to oil shale formation. In the deep lakes far away from delta-turbidite fan deposition systems, low deposition rates and the lack of deposit supplies were not beneficial to the input and enrichment of organic matter.