To reduce heavy metal content in molten slag discharged from the ruching process of municipal solid waste, the volatilization behavior of lead from simulated molten slag was studied. Experimental studies were conducted to determine the apparent volatilization rate of lead from simulated molten slag samples composed of CaO-SiO2-Al2O3 at temperatures of 1673 and 1773 K. The effects of slag composition, ruching temperature and the atmosphere of O-2-N-2 or CO-CO2-N-2 mixed gas oil the volatilization rate were investigated. It was found that the volatilization rate of lead was higher from the slag with a high content of CaO and low contents of SiO2 and Al2O3 in ail oxidizing atmosphere. The rate of volatilization was closely related to the slag viscosity, which depended oil slag composition. At the higher temperature, the rate of volatilization was enhanced with a decrease in slag viscosity caused by temperature rise. It was also found that the rate of volatilization of lead was significantly increased in a reducing atmosphere compared to an oxidizing atmosphere, with an increase in the concentration ratio of CO to CO2 in CO-CO2-N-2 mixed gas.