The market demand for battery-grade lithium carbonate is increasing with the rapid development of the battery industry.The lithium-containing industrial waste from a company was used as raw material,and it was purified by carbonization decomposition method,and the filtrate filter cake cycle was repeated,and finally the battery-grade lithium carbonate meeting the requirement of the industry standard was obtained.The reaction conditions of the carbonization process was as follows：the solid-liquid mass-volume ratio was 1:50,the stirring speed was 300 r/min,the CO₂ flow rate was 10 L/min,the reaction tem-perature was 20 ℃ and the reaction time was 60 min.The reaction conditions of the thermal decomposition process was as follows： the stirring speed was 300 r/min,the reaction temperature was 95 ℃ and the reaction time was 60 min.After a five-stage filtrate cake cycle for the Li₂CO₃ obtained by the carbonization-and decomposition-processes,the final purified Li₂CO₃ product can fully meets the requirement of battery-grade lithium carbonate industry standard.The content of Li₂CO₃ in the product was 99.71%,the mass fractions of Mg,Ca and K were reduced to 0.005 3%,0.005 0% and 0.000 9%,respectively.The yield was maintained above 55%,and the product had a rod shape,uniform size and good dispersion.