[Objectives]  To analyze the carbohydrate content and the activity of key carbohydrases in Hepialus yushuensis larvae, the dominant host of Cordyceps sinensis in the main C. sinensis producing areas of Qinghai province, in order to investigate the mechanism underlying adaptation of H. yushuensis larvae to the Tibetan Plateau’s cold environment where they are predominantly found in alpine meadows at an altitude of 3 000-5 000 m and an annual average temperature of < 5 ℃. [Methods]  4^th instar larvae of H. yushuensis were randomly assigned to one of three treatment groups which were kept at temperatures of 5, 15 (control), or 25 ℃ for 1, 2, or 4 hours. At the end of each experiment, the glycogen, fructose, trehalose and sorbitol content of larvae, and their trehalase, glycerol 3-phosphate dehydrogenase and glycerol 3-phosphate dehydrogenase activity, were measured. [Results]  Glycogen content was significantly lower in the 25 ℃ treatment group, than the 15 ℃ control group (P<0.05). Trehalose, fructose and sorbitol content were higher in the 5 ℃ treatment group than in the 25 ℃ group (P<0.05). Trehalase activity was significantly lower in the 5 ℃ treatment group, and significantly higher in the 25 ℃ group, than in the control group (P<0.05). Glycerol 3-phosphate dehydrogenase and glyceraldehyde-3-phosphate dehydrogenase activity were significantly higher in the 5 ℃ group than in the control group (P < 0.05), indicating that low temperature may accelerate conversion of glycogen and other sugars into smaller, cold-resistant substances to improve cold-tolerance. [Conclusion] Glycogen catabolism in H. yushuensis larvae appears to be closely related to increased monosaccharide and sugar alcohol content. The tendency for catalytic alterations of three key carbohydradases is consistent with observed changes in 4 kinds of carbohydrates. The carbohydrate metabolism in H. yushuensis larvae is regulated by trehalase, glycerol 3-phosphate dehydrogenase and glyceraldehyde-3-phosphate dehydrogenase.