The present study was aimed at examining the energy budget during lactation in small mammals, within which the factors limiting maximum sustained energy intake (SusEI) and the physiological mechanisms underpinning the limitation would be further explored. Body mass, food intake, litter size and litter mass during lactation were determined in striped hamsters raising natural litters (Con), minus 2-3 (Minus) and plus 2-3 pups (Plus) at 21℃, 30℃ and 5℃. Basal metabolic rate (BMR), nonshivering thermogenesis (NST), cytochrome c oxydase (COX) activity of brown adipose tissue (BAT), serum T3, T4 and prolactin levels also were measured. Females increased food intake, but decreased body mass throughout lactation, during which the differences between 21 and 30℃ were not significant. Maximum asymptotic food intake averaged 14g/d, and it was lower by 20.3% and 18.6% in Minus group than Con and Plus groups, respectively. The effect of temperature on food intake was significant. Food intake was increased to 16g/d at 5℃, which was significantly higher than that at 21 and 30℃ (by 14%, P<0.05). Litter size decreased significantly in Plus group, but did not change in Con and Minus groups throughout the lactation. Mean litter size was 4.5±0.3, 2.6±0.3 and 4.6±0.3 in Con, Minus and Plus groups, respectively, at weaning (P<0.01), and no difference was observed between Con and Plus groups. On weaning day, litter mass was not different between Con and Plus groups, but it was significantly lower in Minus group (33.9±3.8 g) than Con (50.9±2.2 g) and Plus groups (49.0±1.8 g). Mean pup body mass was 13.7±0.7 g in Minus group, which was higher by 17.9% and 24.9% than that in Con (11.6±0.5 g) and Plus (10.9±0.6 g) groups (P<0.05), respectively. BMR, NST, BAT COX activity, serum T3, T4 and prolactin levels were significantly higher at 5℃ than 21℃ and 30℃, whereas no differences were observed between 21℃ and 30℃. It suggested that SusEI was 5×BMR in striped hamster raising different litter size at 5℃, 21℃ and 30℃. Cold-exposed hamsters were able to increase energy intake to cope with the energy expenditure for thermogenesis, showing a trade-off energetic budget between maintenance and reproductive output. The finding provided support for the “heat dissipation limitation hypothesis”, but was also consistent with the prediction of the “peripheral limitation hypothesis”.