Abstract The post-fattening period is regarded as the transitive period from euthermia to hibernation in fat-storing hibernators, within which hibernators are characterized by gradually decreased food intake, body mass and body temperature (Tb). This study sought to test the effects of leptin on energy balance and thermoregulation in post-fattening Daurian ground squirrel (Spermophilus dauricus), a typical fat-storing hibernator. The animals were treated with leptin (0.5μg/day), leptin antagonist (0.5μg/day leptin + 5μg/day leptin antagonist) or artificial cerebrospinal fluid (control group) through intracerebroventricular injection for 4 weeks. The last week of administration was coupled with cold exposure (5±1oC) in constant darkness for facilitating torpor. Body mass, energy intake, resting metabolic rate (RMR) and Tb were measured throughout the experiment. The mass of white adipose tissue (WAT), uncoupling protein 1 (UCP1) content in brown adipose tissue and the concentration of energetics-related hormones in serum were measured at the end of drug administration. The results showed that food intake, body mass and Tb spontaneously decreased after fattening. In the control group, 50% animals fell into the torpid state after cold exposure. Leptin administration had no effect on ratio of animals entering torpor. However, the hibernation expression and T4 concentration in the leptin antagonist group were significantly higher than those in the leptin-administrated group. Leptin and leptin antagonist administrations decreased WAT mass by about 25% compared with that in the control group. There were no significant effects of leptin and leptin antagonist administration on energy budget and UCP1 content. Our results suggest that leptin has limited roles on energy regulation but can affect the torpor patterns in the post-fattening Daurian ground squirrels.