Major breakthroughs of shale oil exploration have been made recently in the upper member of the Lower Ganchaigou Formation (E23) of the Paleogene in the Yingxiongling area of the western depression, Qaidam basin. The sedimentary environment of the upper member of the Lower Ganchaigou Formation belongs to a typical saline lake basin. Based on core observation and analysis of X- ray diffraction, whole rock mineral, geochemistry and reservoir physical properties, it is found that the shale and shale oil formed in this environment have the following obvious characteristics: ① the shale is dominated by carbonate minerals, and the lithology is dominated by laminar dolomite limestone and layered lime dolostone; ② the source rock has the characteristics of low TOC and high conversion rate, high free hydrocarbon content and obvious “oil crossover”. Moreover, the oil- bearing property and hydrocarbon generating potential of shale are positively correlated with the carbonate mineral content; ③ the reservoir is characterized by ultra- low porosity and permeability. The clay mineral type is mainly illite and chlorite & illite mixed clay, which is conducive to the stable and high yield of shale oil; ④ the formation pressure coefficient is high, the energy is sufficient, the crude oil has many light components, and the gas oil ratio is high. The E23 shale series in the western Qaidam depression has a large thickness and a wide area. In order to evaluate its resource potential, the western Qaidam depression is divided into four sags, namely, Xiaoliangshan, Yingxiongling, Zhahaquan and Mangya. First, the genetic method is used to calculate the resource quantity, and then the volume method, capacity method and analogy method are used to verify the reliability of the results. Finally, the Delphi method is used to determine the total resource quantity of shale oil as 6.9 billion tons. The research results of this paper are important because ① the unique geological characteristics of shale oil in the salinized lake basin are clarified, and the lithologic association of the rich oil- bearing series is highlighted; ② the calculation formula for calculating adsorbed hydrocarbon is proposed, and a set of practical and feasible evaluation methods for shale oil resources are provided; ③ the estimation of resources confirmed that the western Qaidam depression has considerable shale oil resource potential and strengthened the exploration confidence; ④ the area of type I favorable zones comprehensively determined by multiple factors is 2460 km2, which identifies the practical field of next exploration.