Abstract: This study aims to systematically evaluate the hydrocarbon generation potential of the saline lacustrine mixed-source rocks in the upper member of the Lower Ganchaigou Formation in the Yingxiongling structural belt of the Western Qaidam Depression in the Qaidam Basin, and to reveal the organic matter-rich development model. By combining organic and inorganic geochemical methods, a systematic geochemical analysis was conducted on mixed sedimentary rock samples of different lithologies from the study area, focusing on organic matter abundance, type, maturity, and sedimentary environment characteristics, thereby reconstructing the depositional process of the source rocks. The results showed that the mixed sedimentary rocks in the upper member of the Lower Ganchaigou Formation in the Qaidam Basin generally met the criteria for good to excellent source rocks, with argillaceous shale and calcareous shale exhibiting particularly outstanding performance, showing an average TOC content of 1.37% and hydrocarbon generation potential exceeding 8.36 mg/g, significantly higher than source rocks of other lithologies. The organic matter in the source rocks was dominated by Type Ⅰ to Ⅱ kerogen, mainly derived from lower aquatic organisms such as bacteria and algae, with its thermal evolution at the low to mature stage. The source rocks were deposited in a highly evaporative saline lacustrine environment under a hot and arid paleoclimate, where significant water salinity stratification led to stable anoxic-reducing conditions at the bottom, effectively promoting organic matter preservation. Provenance analysis revealed that the sediments were primarily derived from felsic igneous rocks, and moderate paleoproductivity provided the material basis for organic matter enrichment. The study proposed that under arid climate and shallow-water depositional conditions, salinity stratification-induced reducing to strongly reducing bottom-water environments were the key mechanisms for the enrichment of bacterial and algal organic matter in calcareous/argillaceous shales. The findings provide new insights into the formation mechanisms of saline lacustrine source rocks and offer guidance for oil and gas exploration in the Qaidam Basin and similar regions.