Abstract: In the northern China, the contradiction between ventilation and insulation of sheepfolds is a significant issuein winter . To address the conflict between ventilation and thermal insulation in winter in northern China, 216 healthy male Small-tailed Han sheep were selected as experimental animals with similar initial body weight (33.99 ± 1.25) kg. The animals were randomly allocated to three differently ventilated treatment at the Balin Left Banner experimental based in Inner Mongolia Autonomous Region, including traditional ventilation, reverse ventilation 1 (the fresh air exchange system), and reverse ventilation 2 (the fresh air exchange system + air-source heat pump). The basal diet of the experimental sheep consisted of peanut straw, corn, soybean meal, corn distillers grains, wheat bran, and premix. The effects of three ventilation modes were systematically investigated on production performance, serum parameters, slaughter characteristics, meat quality, and economic profit. The results demonstrated under traditional ventilation, no significant daytime difference was detected between indoor and outdoor temperatures, whereas indoor temperature was 5.6 ℃ higher at night (P < 0.05), indicating that traditional ventilation provided effective insulation only at night. In contrast, indoor temperatures under both reverse ventilation 1 and reverse ventilation 2 were significantly higher than both outdoor temperatures and those recorded under traditional ventilation throughout the entire diurnal cycle (P < 0.05), with mean values consistently maintained above 6.2 ℃. These findings demonstrated that the reverse ventilation strategies effectively modulated the temperature differential between the interior and exterior, thereby achieving sustained thermal insulation within the facility. The sheep in reverse ventilation 1 exhibited significant increases in the final body weight (3.8%), average daily gain (5.4%), and dry matter intake (1.9%) compared to the traditional ventilation (P < 0.01). Both reverse ventilation systems significantly enhanced antioxidant capacity and immune function of the sheep (P < 0.05). Reverse ventilation 1 showed superior slaughter performance and meat quality parameters compared to the traditional ventilation and reverse ventilation 2 (P < 0.05). Both reverse ventilation 1 and reverse ventilation 2 significantly increased the level of color a* and the proportion of unsaturated fatty acids in fattening mutton (P < 0.05). The economic profit of reverse ventilation 1 is 0.14 yuan higher per head per day than that in the traditional ventilation, and 0.44 yuan higher per head per day than that in reverse ventilation 2. This study conclud that reverse ventilation strategies effectively resolve the ventilation-insulation paradox in northern winters by improving environmental conditions (reducing humidity and CO₂ concentration), mitigating oxidative stress, and ultimately enhancing growth performance while optimizing long-chain fatty acid profiles in mutton. Notably, reverse ventilation 1 achieve better husbandry outcomes compared to the reverse ventilation 2 system equipped with heat pump-supplemented. Based on the above results, adopting the reverse ventilation 1 maintains an environment within the optimal growth range for the animals, improves growth performance and meat quality, and achieves higher economic returns in northern China regions during the winter.