Abstract: The landfill is one of the main ways to dispose of municipal solid waste incineration fly ash (MSWIFA). However, the potential leaching of heavy metals from fly ash (FA) with leachate poses a significant risk to the environment. The main pretreatment method is the solidification of heavy metals in fly ash by pharmaceuticals. In particular, chelating agent-based solidifying agents are more effective in curing heavy metals in fly ash and are widely used at home and abroad. In this paper, by comparing the heavy metal curing rates of various organic chelating agents, it is found that chelating agents with different functional groups (aldehyde group, hydroxyl group, carboxyl group, phosphate functional group, and sulfur-containing functional group) have significant differences in the solidification effects. For solidifying heavy metals in FA, the chelating agents with phosphate and sulfur functional groups are generally more effective than the chelating agents with aldehyde, hydroxyl, and carboxyl functional groups. Therefore, according to the acidity and alkalinity of the landfill leachate, the landfill leachate can be made neutral by adding carboxyl, hydroxyl, or phosphate functional group modified organic chelating agent. After solidification, the solidified product forms an orthotetrahedral chelate to achieve the most stable structure thus reducing the leaching rate of heavy metals from the MSWIFA and reducing landfill pollution.