Ventilation is an important means to control the environment of piggery. Ventilation in different seasons and different areas need different schemes due to different outdoor temperatures. One is to increase the air flow to make pigs feel comfortable under high temperatures, so as to mitigate the adverse effects of high temperatures on pigs; Under the condition of suitable outdoor temperature, it is sufficient to introduce an appropriate amount of fresh air to discharge the dirty air and moisture in the pig house, so as to improve the air environment of the pig house and reduce the number of microorganisms in the air in the pig house. The third is the outdoor cold season, so it is necessary to increase the temperature of the introduced fresh air to prevent the cold air from blowing directly into the pig house. The first is to conduct heat recovery of the discharged air in the pig house, The heat of exhaust air and fresh air in the house is exchanged by air-air plate heat exchanger or runner heat exchanger. In addition, in extreme cold conditions, it is necessary to use heat coils to properly heat the fresh air.