Abstract: In order to solve the leaching problem of chloride salts and heavy metals in co-disposal of membrane concentrate and incineration fly ash in domestic waste landfills, the nanofitration membrane solution from a municipal solid waste landfill in Beijing was used to leach incineration fly ash from a domestic waste incineration plant in Beijing under different liquid-solid ratios and acid-alkaline conditions, and the leaching characteristics of Cl and heavy metal migration were investigated. The results showed that the total chloride dissolution rate in incineration fly ash was 81%, 76% and 61% under the liquid-solid ratios of 12∶1, 8∶1 and 4∶1, respectively. The higher the liquid-solid ratio, the lower the packing height, and the more sufficient chloride ion dissolution. The total chloride dissolution rate significantly increased at the nanofiltration membrane concentrate pH of 3.20 and 10.70 when the adsorption of chloride ions was competitive with that of oxygen-containing anions under the liquid-solid ratio of 4∶1 compared with the unadjusted pH, which was 81% and 83% under different liquid-solid ratio and acid-base conditions. Analysis of the leached ash using XRD showed that no mineral phases of NaCl and KCl were not detected in the leached ash. The leaching concentrations of heavy metals Pb, Zn, Cu, Cr, Cd and Hg in the leachate met the requirements of the Standard for Identification of Hazardous Wastes: Leaching Toxicity Identification (GB 5085.3-2007) and the Standard for Pollution Control of Domestic Waste Landfills (GB 16889-2008) after changing the pH of the nanofiltration membrane concentrate to 3.20 and 10.70. The study showed that the membrane concentrate leaching of fly ash can remove chloride salts and some heavy metals from incineration fly ash, and the leached ash residue can be burned after thermal treatment to remove the organic matter in the nanofiltration membrane concentrate, and the ash residue is expected to achieve safe resource utilization after thermal treatment.