The volatilization of heavy metals Pb, Cd, Cu and Zn were studied at 900 degrees C and 1 000 degrees C with different residence time, meanwhile the influence of chlorination agents CaCl2, MgCl2, NaCl, FeCl3 and AlCl3 on heavy metals volatilization was studied. The results showed that the volatilization of heavy metals had great differences with the volatilization rate followed the order Pb > Cd > Zn > Cu, in which the volatilization rate of Pb was more than 80% and that of Cu was less than 30%. In the thermal disposal process, the volatilization rate influenced by temperature was greater than that by the residence time, and the volatile elements Pb and Cd were particularly evident in the volatilization. After adding chlorides in fly ash, the volatilization of heavy metals changed significantly, and the volatilization rate of the low volatile elements Cu and Zn increased significantly compared with Pb and Cd. With the content of chloride increasing, the volatilization rate of heavy metals increased, but different types of chloride compounds on heavy metal transformation were quite different, in which the promotion effect of NaCl on heavy metals Cd, Zn and Cu was less than that of other chlorinating agents. The results can provide strategies for the harmless disposal and maximize resource utilization and recycling of fly ash.