Abstract: In the smelter of lead and zinc, the thallium bearing zinc ash was yielded during the volatilization of lead and zinc slag, and it is the main enrichment of thallium. In this paper, water, H₂SO₄ and NaOH solution were used to leach the ash, and the effects of concentration and temperature on the leaching of zinc and thallium were investigated. The results show that the leaching rate of thallium increases slowly with the increasing of temperature, and reached 78% above 70 ℃. The selectivity of acidity leaching for zinc and thallium was poor. The leaching rate of thallium and zinc reached 79% and 85% under the conditions of H₂SO₄ concentration of 40 g·L^-1 and temperature of 70 ℃. While the alkalinity leaching has an excellent selectivity for thallium and zinc, the leaching rate of thallium increases with the increasing of alkali concentration. Under the optimum conditions of NaOH 40 g·L^-1 and temperature 70 ℃, the leaching rates of thallium and zinc are about 91% and 1%, respectively. Therefore, alkaline leaching was used for leaching of Tl bearing ash. The product thallium, with a purity of 92.84%, was obtained by sulfide precipitation, H₂SO₄ leaching and Zn plate replacement of lixivium. The new process achieves the resource utilization and open-circuit of thallium from ultra-low thallium ash, and has the advantages of simple process and good selectivity.