Abstract: Abstract: In order to provide a warm, dry and airy environment for calves, a greenhouse barn was designed and constructed. The traditional calf barn was used as controls, thermal environment and air quality were monitored and the application effect was evaluated. The front part of the greenhouse barn was covered with two-layered plastic films with 0.2 meter between the two plastic films. The plastic films made a 66 degree angle with the ground. The roof of the greenhouse calf barn was constructed with two-layered color steel plates, while the space between the steel plates was filled with polystyrene foam board (0.12 m). The wall of the barn was built with two-layered fiber reinforced inorganic board, while the space between the boards was filled with polystyrene foam board (0.20 m). Natural ventilation system was used for greenhouse barn. There were two insulated air-inlet flues on the gable, and two insulated air-outlet flues on the ridge. The top end of the air-outlet flues was 0.7 meter above the ridge and its lower end extended 0.8 meter into the barn. There were ten calf hutches in the barn. The calves were raised individually. The environmental measurements showed that, when outdoor average temperature was -17.3 ℃ and outdoor relative humidity was 68%, the average temperature and the average internal surface temperature inside the greenhouse calf barn were -0.7 and 0.8℃, respectively, which were 3.8 and 6.7℃ respectively higher than those in traditional calf barn. This illustrated that the design of heat insulation met the requirement of calf barn in cold regions. The relative humidity in the greenhouse calf barn was 59 %. The ammonia was undetectable. The concentration of carbon dioxide was 2441 mg/m3 in contrast to 95 %, 3.9 mg/m3, and 3096 mg/m3 in traditional calf barns, respectively. This illustrated that the design of ventilation system met the requirement of calves in cold regions. Average temperature, average internal surface temperature and relative humidity of calf hutch in the greenhouse calf barn were 0.9℃, 5.7℃ and 65%, respectively. These suggest that the calf hutches in greenhouse calf barn not only achieved appropriate ventilation for calf barns during winters, but also provided a draught-free environment for calf. Optimum temperature and good air quality in the greenhouse calf barn reduced the calf morbidity and mortality rates in 0-60-day-old calves to 33.33 % and 0 %, respectively. Compared with the traditional calf barns，the calf morbidity and mortality rates in 0-60-day-old calves were as high as 71.43% and 28.57 %, respectively.