Ventilation system suitable for pig building

The ventilation system suitable for the pig building comprises a building body and ventilation equipment, the building body comprises a negative pressure chamber, an air shaft and a plurality of floors, the negative pressure chamber is located on the roof of the building body and communicated with the air shaft, the air shaft is communicated with the floors, and each floor is provided with a first side wall, a pig house and a second side wall. The first side wall is provided with a fresh air inlet, the hog house is provided with a breeding area and an underground air duct, the underground air duct is located below the breeding area and provided with an air duct inlet and an air duct outlet, the air duct inlet is adjacent to the fresh air inlet, the air duct outlet is communicated with the breeding area, the second side wall is provided with an air shaft inlet, the air shaft is adjacent to the second side wall, and the air shaft inlet is communicated with the air shaft. The ventilation equipment comprises a fa