Gas circulating and purifying device for breeding house

One end of an air supply pipeline penetrates through a first installation hole to be located in a first purification chamber, the other end of the air supply pipeline is communicated with the interior of the breeding house, a purification channel penetrates through a modified activated carbon body, and one end opening of the purification channel is communicated with the end opening, located in the first purification chamber, of the air supply pipeline. The other port of the sulfuric acid tank is communicated with one port of the conveying channel, and the sulfuric acid tank is close to the other port of the conveying channel; a through hole is formed in the joint of the second purification chamber and the first purification chamber in a penetrating mode, a sodium hydroxide solution discharging device is installed in the second purification chamber, and meanwhile the second purification chamber is communicated into the breeding house through an air outlet pipeline. The controller is electrically connected with