The spherical CoCO3 precursor was prepared by precipitation method using CoSO4 as cobalt source and NH4HCO3 as precipitating agent. The influence of seed crystal quantity, pH value, and cobalt source solution flow rate on morphology, distribution of particle size, tap density and sulfur content of CoCO3 was investigated. Meanwhile, the growth mechanism of cobalt carbonate was studied.CoCO3 precursor was calcined at different heating-up time in order to optimize the physical and chemical properties of Co3O4.The results show that large-size spherical Co3O4 with narrow particle size distribution and high tap density could be obtained in a 10L reactor with 2 kg seed crystals and cobalt source flow rate at 500 mL/h at pH value 7-7.3, and then calcined in 3 stages, with 60 minutes heating-up time for each stage. The median particle diameter of Co3O4 was 16.5 μm and tap density was over 2.2 g/cm3.