A process for preparing battery-grade lithium carbonate with lithium-rich solution obtained from the low lithium leaching solution of fly ash by adsorption method was proposed. A carbonization-decomposition process was used to remove impurities. First, primary Li2CO3 was treated by CO2 to get the more soluble bicarbonates. The decomposition of LiHCO3 produced insoluble Li2CO3 at 90 ℃. And Li2CO3 was smashed by air stream pulverization. The final precipitation yielded a high purity (99.6%) and homogeneous Li2CO3. Some factors affecting the production efficiency were investigated. The results showed that a liquid-solid ratio of 25: 1, a carbonization temperature of 25 ℃, an air velocity of 2 L/ min, and a stirring speed of 400rpm; a decomposition temperature of 90 ℃ and a stirring speed of 400rpm, a molar ratio of EDTA to Ca 2:1; an air pressure of 0.3Mpa and hot water washing precipitate (L/S mass ratio 2:1) promoted ions removal.