Air breather and gearbox

The invention provides an air breather and a gearbox. The air breather comprises an elastic pipe body and a breathable water-absorbing part, wherein the two ends of the elastic pipe body are providedwith breather vents correspondingly, so that paths of gas circulation are formed between the two ends of the elastic pipe body, and one end of the elastic pipe body forms a connector connected with ashell; the breathable water-absorbing part is accommodated in an accommodating cavity at the other end of the elastic pipe body, the connector is provided with a first large diameter section, a smalldiameter section and a second large diameter section which are sequentially arranged along the axial direction of one end of the elastic pipe body, the first large diameter section is arranged insideshell and is connected to the shell, the small diameter section is arranged in an opening, the second large diameter section is arranged outside of the shell and is connected to the shell, the radialdimension of the first large