A process for recovering Co and preparing microspherical Co₃O₄ through NH₃ distillation and phase transformation from ammoniacal solution was investigated. As the basis of thermodynamics, the solubility of Co at different NH₃ and CO₃^2- concentrations was studied, and then the effects of different NH₃ distillation conditions on Co recovery rate were discussed. Over 94% Co and 96% NH₃ were recovered through NH₃ distillation, and the cobalt was precipitated in form of cobalt carbonate ammonium compound salt. Through the analysis of the formation mechanism of the precursor, the precipitation process of cobalt could be divided into two stages, and the cobalt precipitation rate was significantly accelerated in the second stage. In phase transformation, the effect of temperature on the roasted product was investigated. The microspherical Co₃O₄ with a microporous structure was prepared at 300 °C, and Co₃O₄ with a mesoporous structure and high-spin state was obtained at 750 °C.