The present invention relates to an oxygen electrode bifunctional catalyst, its preparation method and its application. Firstly, a carbon carrier is used as a reducing agent, and an iridium salt is reduced and reacted with an iridium salt at high temperature to obtain elemental iridium, that is, the elemental iridium is loaded on the surface of the carbon carrier to form Ir / C; Then Ir / C is used as the carrier, ethylene glycol is used as the reducing agent, and Ir / C is mixed with platinum salt, cobalt salt and tungsten salt, and reacted at a constant temperature in an oil bath to realize the formation of elemental platinum, cobalt, and tungsten on Ir / C. Precipitate to obtain the catalyst PtCoW-Ir / C. The preparation method of the present invention is easy to operate and has strong operability. The prepared composite catalyst shows an obvious two-phase structure of simple substance Ir and PtCoW and is uniformly dispersed. The composite catalyst can be used in acidic environment Catalyzes oxygen reduction and oxygen evolution reactions, the electrocatalytic oxygen reduction reaction performance in acidic environment is better than commercial Pt / C, and the electrocatalytic oxygen evolution reaction performance is better than commercial iridium dioxide.