Heavy metal chemical stabilization with synthesized heavy metal chelating agent was assessed for flyash from municipal solid waste incinerator. Flyash can contain heavy metals (e.g. Pb, Cd) which can leach. A new kind of heavy metal chelating agent showed more attractive competition than inorganic chemicals in stabilizing flyash. The synthesizing method of this kind of heavy metal chelating agent was explained in this paper, and the technology process and treatment efficiency of the chelating agent in treating flyash were experimentally studied, which was compared with the results of inorganic chemical agents such as sodium sulfide and lime. The heavy metals in flyash were stabilized more effectively by using heavy metal chelating agents than by using sodium sulfide and lime, furthermore, the stabilized products using the chelating agents can meet the landfill disposal controlling standards for heavy metal waste. pH-dependent leaching experiment showed the stabilized flyash by treatment with heavy metal chelating agent could keep long-tern stabilization within a broad range of pH value. Thus, the risk of secondary pollution for the stabilized products was reduced dramatically when the environment condition changes during its disposal period. (C) 2004 Elsevier B.V. All rights reserved.