The leaching characteristics of chloride and heavy metals in the washing process of waste incineration fly ash from mechanical grate furnace were systematically studied,and the existing forms of heavy metals in the washing solution were simulated and analyzed by Visual MINTEQ.The results showed that the chlorine state in fly ash mainly existed in the form of soluble sodium chloride（NaCl）,potassium chloride（KCl）,calcium chloride（CaCl₂） and basic calcium chloride（CaClOH）.More than 97% of the leaching components of fly ash were Cl^-,Na,K and Ca,of which Cl^- accounts for 60%.The leaching amount of heavy metals and other components was very small,less than 1%.The removal effect of water washing on chloride ion was very obvious,up to more than 92%,but the leaching amount of heavy metals in the process of water washing was very low.The optimum conditions for single water washing of fly ash: the volume mass ratio of liquid to solid was 6 mL/ g and the washing time was 10 min.The analysis of visual MINTEQ model showed that pH was an important factor to control the forms of lead（Pb）,copper（Cu）,zinc（Zn） and cadmium（Cd） in fly ash washing solution,and chloride ion（Cl^-） also had an important influence on the form distribution of cadmium.There was an excellent linear correlation between the conductivity of fly ash washing solution and the mass concentration of chloride ion,which could be used as an effective indirect index to monitor the change of mass concentration of chloride ion in leachate.