Tetraena mongolica is a rare xerophytic shrub native to arid regions of western China. T. mongolica, commonly known as "oil firewood," was once used as an important fuel source by local herders. To understand lipid accumulation and metabolism in the non-seed organs of T. mongolica, we analyzed lipid content in its roots, stems, and leaves. We identified 450 lipids, of which 78 were triglycerides (TGs), making it the most diverse subclass. Roots and stems accumulated significantly higher levels of total lipids and TGs than leaves, and both lipid fatty acids and total fatty acids showed similar accumulation patterns across different organs. A total of 38 fatty acids were detected in T. mongolica lipids, with C16:0, C18:1, and C18:2 being the dominant TG components across all organs. In the analysis of total fatty acids, hydroxy fatty acids and dicarboxylic acids emerged as the most abundant. By integrating the relative content of lipid fatty acids with transcriptome analysis, we identified 15 core genes involved in the lipid metabolism pathway and also identified genes with a high level of association with these pathways. The expression levels of these genes were determined to be closely correlated with the accumulation of relevant lipids, suggesting that they play important roles in the regulation of fatty acid and oil metabolism. This study presents a systematic analysis of lipid metabolism in the non-seed organs of T. mongolica, offering a new theoretical foundation for utilizing vegetative organs from extreme environments as alternative sources of plant oils and biofuels.