Coal ash melting characteristics has a direct impact on the smooth operation of entrained gasifier. Mineral conversion of coal ash is very significant to be investigated, because the mineral can affect the melting temperature and viscosity under high temperature conditions. In this paper, the effects of different Al2O3/CaO on the mineral conversion, melting temperature and viscosity of Ningdong coal ash are studied by the combination of experiment and simulation. The trend of melting temperature decreases firstly and rises with increasing Al2O3/CaO. The ash melting point reached to the lowest when the ratio is 123. XRD and Factsage software are used to analyze crystallization behavior of samples. The results show that the content of anorthite, albite and corundum increases and subsequently decreases, while the content of mullite decreases firstly and then rises with increasing Al2O3/CaO. High content with CaO can contribute to form albite and anorthite of low-melting. Besides, high content with Al2O3 can tend to produce mullite of high-melting. The results of experimental and simulation arc basically the same, which lays a foundation for the melting characteristics of Ningdong coal ash and can provide technical support for the smooth operation of the entrained-gasifier. (C) 2020 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.