Melting characteristics of MSW incineration fly ash was analyzed by high temperature tubular furnace in the paper, including the material migration of fly ash at high temperature and the leaching analysis of molten glass. The results show that with the increase of reaction temperature, the molten slag produced by fly ash melting decreases relative to the original fly ash, and the volatile matter of fly ash increases at high temperature. The density of the melt vitreum is 5 times more than the stacking density of fly ash, which has good volume reduction effect. The content of chloride ion in fly ash slag became less, most chlorine elements volatilized into gas phase and secondary fly ash. The influence of the Cl- entering gas on the corrosion caused by the melting system will be a process problem to be solved in the future.