The invention relates to a sealed type air flotation machine. The sealed type air flotation machine comprises an air floatation tank, a residue scraping device, a circulating blower, a bubble releaser and a gas dissolving system. The air floatation tank is of a sealed tank body structure, and a contact tank, a separation tank, a clean water tank and a scum tank are arranged in the air floatation tank. A clean water pipe is arranged at the bottom of the separation tank and communicates with the clean water tank. The gas dissolving system comprises a reflux pump, a gas dissolving tank and an air compressor, one end of the reflux pump is connected with the clean water tank, the other end of the reflux pump is connected with a water inlet of the gas dissolving tank, a water outlet of the gas dissolving tank communicates with the bubble releaser mounted at the bottom of the contact tank, and a gas inlet of the gas dissolving tank is connected with the air compressor. The circulating blower is connected with the gas dissolving tank and the air floatation tank so as to blow fetid or toxic gases generated inside the air floatation tank into the gas dissolving tank, gas-dissolved water formed again enters the contact tank, and thus, the fetid or toxic gases are not directly exhausted into air, so that no secondary pollution is caused; the gas loss is low and is close to zero loss.