Abstract: Abstract: In order to explore the effects of quantitative mechanical ventilation on the environment of the lactating house and the reproductive performance of sows in South China, the study measured and compared the effects of natural ventilation and quantitative mechanical ventilation on the environmental temperature, humidity, carbon dioxide, ammonia concentration, reproductive performance, respiratory rate, rectal temperature and other indicators in lactating houses of Liangguang Xiaohua pig in winter. The results showed that under the experimental conditions, the natural ventilation mode and the quantitative mechanical ventilation mode had no significant difference in the ambient temperature and humidity of the lactating house. However, during the night time, the concentrations of carbon dioxide and ammonia in the naturally ventilated lactating house were (817.16±25.28) mg/m3 and (7.88±0.34) mg/m3, respectively, which were significantly higher (P<0.01) than the carbon dioxide ((645.71±9.49) mg/m3) and ammonia ((5.59±0.14) mg/m3) in the quantitatively mechanically ventilated lactating house. The concentrations of carbon dioxide and ammonia throughout the day in the naturally ventilated nursing house were (707.34±20.42) and (6.63±0.27) mg/m3, respectively, which were also significantly higher (P<0.01) than the carbon dioxide ((583.25±10.06) mg/m3) and ammonia ((4.81±0.13) mg/m3) in the quantitatively mechanically ventilated lactating house. Moreover, the number of litter sizes at birth under the quantitative mechanical ventilation mode was (12.50±0.55), which tended to be higher than that under the natural ventilation mode (11.13±0.66) (P=0.08). In addition, the average daily weight gain of piglets in the quantitative mechanical ventilation mode was (146±40) g, which tended to be higher than that in the natural ventilation mode (133±70) g (P=0.09). However, compared with the quantitative mechanical ventilation, the average daily body weight loss (P=0.06) and average daily backfat thickness loss (P=0.08) of sows under the natural ventilation mode tended to be reduced. On the 21st day of lactation, the respiration rate of sows in natural ventilation mode was (69.50± 3.85) times/min, which was significantly higher (P<0.05) than that in quantitative mechanical ventilation mode (57.29± 1.54)?times/min. In conclusion, under this experimental condition, compared with natural ventilation, the quantitative mechanical ventilation mode improved the air quality and physiological status in the lactating house of Liangguang Xiaohua pig, as well as the growth performance of the piglets in South China in winter.