The invention relates to a method for recovering cadmium from waste nickel-cadmium battery, belonging to recovering treatment of the waste nickel-cadmium battery. The invention provides a method of low-temperature fire oxidation-ammonia leaching flotation. The method comprises the following steps: carrying out crushing and rinsing on the waste nickel-cadmium battery by a crusher, and putting rinsed matters into a muffle furnace for roasting; after roasting, carrying out sieving by a sieve with 80 meshes, and removing an iron shell and a flow-collecting net; carrying out ammonia leaching on the sieved matters in the leachate; after ammonia leaching, adding yellow catching agent and 2 floating oil solution in the leachate, fully stirring, slowly adding sodium sulfide solution, till the solution does not generate orange precipitate, stopping adding the sodium sulfide, continuously stirring in the process of adding the sodium sulfide, floating foam, using a scraping plate to scrape out the foam, namely obtaining cadmium sulfide; after floatation, carrying out press-filtering on the slurry, returning the leachate to ammonia leaching technique, carrying out concentrated treatment on thefilter residue and recovering valuable metal. The method is characterized by simple and easy technique, more common and cheaper material used and equipment, cycle use for ammonia leachate, having no pollution and the like, and the recovery rate of cadmium can reach more than 95 percent.