A breathing apparatus structure with a two-stage reduced-pressure spare air bottle head is provided, which includes an air bottle head mounted at an outlet end of a spare air bottle and an inhalation mouthpiece, so as to provide an air at a suitable pressure to a diver or drowning person for emergency use. The air bottle head is sequentially provided with an air bottle head switch, a high pressure reducing valve, and a low-pressure valve connected in series on an air passage thereof. Thus, an air leakage of a high-pressure air in the air bottle can be avoided when the high-pressure air is not used, and the service life of elastic elements of the low-pressure valve can also be prolonged.