Abstract: Saussurea involucrata Kav et Kir ex Maxim (Compositae) is a folk drug used in China (Chinese: name: Xinjiang Xuelian), from which a new guaiane type sesquiterpene named Xuelianlactone was isolated. The structure of Xuelianlactone (1), mp 129～131℃,C₁₅H₂₀O₃ (High-MS), was proposed as 8β-hydroxy-1αH, 5αH, 6βH, 7αH, 11αH-guaian-10(14), 4(15)-diene-6,12-olide based on IR, ¹H-NMR, ¹³C-NMR and MS spectra data of Xuelianlactone (1) and its monoacetate (1a).