Abstract: Calcium acetate was added into a bituminous coal through physically blending and impregnation to obtain the ble-Ca coal rich in excluded Ca-mineral and imp-Ca coal rich in included Ca-mineral, respectively. The raw coal, ble-Ca coal and imp-Ca coal were burned in a drop tube furnace at 1300℃. The generated particulate matters (PMs) were collected and analyzed to study the influence of different distributions of Ca-mineral in coal on trimodal PM formation during combustion. The results showed that for the three coals, PMs with the ultrafine mode, central mode and coarse mode were all in the size range of < 0.2μm, 0.2-2μm and >2μm, respectively. The included and excluded Ca-minerals can both promote the formation of ultrafine mode PM, and the excluded one had more significant effect. The included Ca-mineral can restrain, while the excluded one can promote the formation of central mode PM. The included Ca-mineral can promote the formation of coarse mode PM, while the excluded one did not have obvious effect.