Abstract: The battery grade Li2CO3 was prepared with industrialgrade Li2CO3 as raw material，and trace sulfur impurities in the product was removed by hydrothermal method.The effects of hydrothermal temperature and hydrothermal time on the re moval of sulfur impurities were investigated.The morphology and structure of the product was characterized by means of scan ning electron microscopy（SEM），X-ray diffraction（XRD） and X-ray photoelectron spectroscopy（XPS）.Results showed that the sulfur impurities mainly existed in the form of Li2SO4 and were adsorbed on the surface of lithium carbonate.The hydro thermal process improved the crystallization of lithium carbonate，reduced the active sites of crystal surface and reduced ad sorption of sulfur impurities on Li2CO3 surface.The purity of lithium carbonate increased up to 99.8% and SO42- mass fraction decreased to 6.30×10-4 after hydrothermal reaction at 140 ℃ for 4 h，both meeting the battery grade lithium carbonate indus try standard，YST 582—2013.

Key words: lithium carbonate；sulfur removal；hydrothermal method