The leaching condition of Li from fly ash has been studied in this paper, which includes analyzing the influence of leaching rate of lithium from the size of baked material particle, the concentration of leaching liquid, the temperature in the leaching process, the dosage of the leaching liquid. The result indicates that the leaching rate of lithium can reach 70% in the following conditions: the baked material of fly ash is grinded into fine particle first and then continue to be grinded into paste with water before leaching the paste with solution of 5% sodium carbonate (fly ash: solution of sodium carbonate = 1: 100) and heat it 2h on 140 ℃. At last, leachate will be obtained after filtering.