In this paper, the pulverized coal combustion was conducted in a 25 kW quasi one-dimensional down-fired furnace to examine the role of minerals in the evolution of fine particulate matter (PM) along the axial length of the combustor. The fine PM, emitted at different stages of coal combustion, was collected with a nitrogen-aspirated, isokinetic particulate sampling probe and classified in size by an electric low-pressure impactor (ELPI+). Extensive computer-controlled scanning electron microscopy (CCSEM) and energy-dispersive X-ray spectroscopy (EDS) analyses were further performed to detect the morphology and component of the fine PM at different size modes (PM0.1, PM0.1-1, and PM1-10). The results indicate that the mass concentration of particulates in the ultrafine mode (PM0.1) decreases, whereas that in the supermicron mode (PM1-10) increases as the residence time of coal particles advances from 0.5 to 1.5 s. At different coal combustion stages, the components of supermicron PM are relatively stable, while those of ultrafine or submicron PM dramatically change, implying their different formation mechanisms. It is found that Na and K together take up a relative content of 20-40% in the PM fraction of 0.042 mu m but less than 15% in that of 2.0 mu m at different residence times in the combustor. Nevertheless, Ca and Mg tend to be ultimately abundant in PM0.1-1, totally accounting for 50-60%. Finally, emphasis is laid on revealing the inherent relationship between the mineral transformation of alkali and alkaline earth metallic (AAEM) species in fine PM and the combustion properties of coal particles.