Abstract: The Yingxiongling shale oil reservoir in Qaidam Basin is a global unique thick saline-lacustrine shale oil reservoir developed in plateau mountainous area, and its main oil beds are in Paleogene. Recently, major breakthroughs have been made in oil and gas exploration in the Yingxiongling shale oil reservoir, and industrial oil flow has been obtained in the formation test of 31 layers of 11 prospecting wells. The cumulative oil production of Well Chaiping1 exceeds 10 000 tons in 295 days, showing good exploration potential and development prospect. This paper systematically analyzes the geological setting and main accumulation factors of the Yingxiongling shale oil reservoir, and establishes the enrichment model of shale oil reservoir. The thick plateau mountainous shale oil reservoir is distinctive in terms of the surface and subsurface conditions, so that the existing theories and technologies of shale oil exploration and development at home and abroad cannot be followed completely. Further research progresses are as follows. (1) The key factors for the enrichment of sweet spots in the Yingxiongling shale oil reservoir include the two-stage continuous and efficient hydrocarbon generation of low organic matter abundance shale in saline lacustrine basin, the good reservoir spaces provided by the bedded and laminated calcite dolomite in the thick mixed sedimentary system, the easy stimulation condition due to reservoir with high carbonate mineral and low clay mineral contents, and the high shale oil recovery due to high formation pressure, high gas-oil ratio and good crude oil quality. (2) There are four kinds of enrichment zones with significant different reservoir spaces developed in the Yingxiongling structural belt, i.e., tectonic-stable zone, fault-deformation zone, fault-fracture/fault-karst zone and inter-salt crumple zone, corresponding to four kinds of sweet spot enrichment models, namely stratabound mode, bed-fracture compound control mode, fault control mode and salt control mode. (3) The Yingxiongling shale oil reservoir is located in a unique plateau mountainous environment. The extremely thick deposits of more than kilometers and the rugged landscape of ravines determine the difficulty and diversity of well sites, well patterns and well types. The cold weather, hypoxia and water shortage also greatly increase the difficulty of exploitation. (4) F our well patterns and development modes can be used to achieve efficient production in the Yingxiongling shale oil reservoir, including the zipper-like fracturing mode for stereo horizontal-well network, separate fracturing and commingling production for cluster vertical well or highly inclined well, multi-layer fracturing communication production mode for vertical well or highly inclined well or directional well, and continuous perforation combined with acidification production mode for directional well. The relevant understandings are expected to provide scientific guidance and technical support for the study of shale oil enrichment mode and efficient production mode, and the practice of well pattern and geological-engineering integration in plateau mountainous area.