Abstract: The disclosure discloses a device and method for recovering lithium from lithium-containing mother liquor in the process of preparing lithium carbonate. The preparation of sodium carbonate solution using the mother liquor produced during lithium carbonate rinsing can recover part of lithium, reduce the water amount required for preparing sodium carbonate and decrease the solvent consumption. The mother liquor generated from lithium precipitation reaction is divided into two parts. One directly flows into the lithium chloride refining unit and mixes with the lithium chloride feed liquor. Carbonate and hydroxide present in this part of lithium-precipitation mother liquor, which can deeply remove the calcium and magnesium ions in the lithium chloride feed liquor, for refining the lithium chloride feed liquor, and removing impurities and recovering lithium from the primary lithium-precipitation mother liquor.