Abstract: The crystal phases, porosity and surface morphology of self-desulfurization residue of Huangling coal ash were studied by XRD, N₂ absorption and SEM.It was found that the total content of sulfation product CaSO₄ and BaSO4 was 8.5% in the self-desulfurization residue obtained at 800 ℃, while that of active CaCO₃ and CaO was 4.9%.The residue surface was composed of many 7.5—15 μm particles that containd some 0.7—1.5 μm button-like particles and pores.However neither CaCO₃,CaO,CaSO₄ nor BaSO₄ were found in the residue obtained at 1200℃,due to thermal decomposition and intense melting.The residue surface was composed of some 30μm particles that containd 3—5 μm nonporous particles with smooth surface.There was a distinct decrease in porosity parameters of the residue when the furnace temperature increased from 800 ℃ to 1200 ℃.