Preparation system and preparation method of battery-grade lithium carbonate

The invention provides a preparation system of battery-grade lithium carbonate. The preparation system comprises a hydrogenation kettle, an impurity remover, a filter and a decomposer, wherein a kettle body of the hydrogenation kettle is internally provided with a stirring shaft and stirring blades, and a flow guide barrel which is provided with openings at upper and lower ends; the preparation system further comprises a plurality of material feeding pipes, a first CO2 introducing pipe and an overflowing hole; the hydrogenation kettle is used for enabling coarse-grade lithium carbonate slurry and carbon dioxide to react to obtain primary hydrogenation liquid; the impurity remover is connected with the overflowing hole and is used for removing impurities in the primary hydrogenation liquid to obtain impurity-removed hydrogenation liquid; the filter is connected with an outlet pipe of the impurity remover and is used for filtering the impurity-removed hydrogenation liquid to obtain filtered liquid; the decomposer is connected with a liquid discharging hole of the filter and is used for thermally decomposing the filtered liquid to obtain decomposed lithium carbonate. The preparation system can be used for realizing continuous production of the battery-grade lithium carbonate; a production flow is shortened and the energy consumption is reduced. The invention further provides a preparation method of the battery-grade lithium carbonate.