Abstract: Using CoCl2·6H2O and NH4HCO3 as raw materials, the CoCO3 precursor with fine, uniform and controllable particle size was prepared by liquid-phase precipitation method, and then ultrafine spherical cobalt powder was prepared by calcination-hydrogen reduction. Scanning electron microscope (SEM), X-ray diffractometer (XRD) and simultaneous thermal analysis (DSC-TG) were used to characterize the microscopic morphology, phase and weight loss ratio of the powder obtained at each stage, respectively. The influence of stirring time and reaction temperature on the particle size and morphology of CoCO3 in the liquid-phase precipitation method was analyzed; the influence of hydrogen reduction process on the phase, particle size and morphology of the reduction product was analyzed. The results show that the nucleation rate of CoCO3 will increase with the increase of stirring time and reaction temperature, and then the average particle size of CoCO3 will decrease. CoCO3 with high sphericity and an average particle size of 0.96 μm. In the process of hydrogen reduction of Co3O4, with the prolongation of hydrogen reduction time and the increase of temperature, the particle size of cobalt powder becomes larger; when the hydrogen reduction temperature is 400 ℃ and the time is 45 min, the average particle size of cobalt