Abstract: Saergan Formation and Yingan Formation are two important marine hydrocarbon source rock units within the Ordovician System of Tarim Basin. Both of these two formations were developed in deep-water sedimentary environments, but they exhibited differences in organic matter abundance, type, and enrichment mechanisms. Based on the outcrop and seismic data from Kalpin area in the northwestern margin of Tarim Basin, the authors in this paper systematically analyzed the sedimentary characteristics and hydrocarbon generation potential of these two source rock units by comprehensively applying organic geochemical and sedimentological methods. The research results showed that Saergan Formation was formed during the Middle to Late Ordovician, associated with anoxic events of that period. The black shale was the major strata and the average total organic carbon (TOC) content was 1.88%, reaching a maximum of 5.50%. The kerogen was in Type II, which was at high maturity-overmature stage, demonstrating enormous hydrocarbon generation potential. Yingan Formation formed in the Late Ordovician, mainly consisting of dark gray to gray-black mudstone and shale. The average TOC was only 0.45% and the organic matter abundance was low, indicating maturity-high maturity stage. The differences between these two source rock units were primarily from variations in paleoproductivity and preservation conditions. Saergan Formation was controlled by high paleoproductivity and high burial efficiency triggered by anoxic events, whereas Yingan Formation was in an anaerobic environment with relatively low paleoproductivity levels. This study not only revealed the controlling mechanisms of tectonic-sedimentary background on the development of marine source rocks, but also clarified the different roles of global oceanic anoxic events and regional tectonic activities in source rock formation. This study could provide important geological evidence for optimizing oil and gas exploration targets and evaluating resource potential in the Ordovician of Tarim Basin, offering practical implications for guiding deep marine oil and gas exploration.