Abstract: Co-combustion of coal and biomass is an effective way to reduce the emission of pollutant and greenhouse gas during power generation. It is of particular importance to concern the particulate matter（PM） emission during this process, as the hazy weather becomes more and more serious in China. Experiment was conducted on a drop tube furnace to study the PM formation characteristics during co-combustion of a typical Zhundong coal and rice husk. The furnace temperature is 1300 ℃, and rice husk was blended with Zhundong coal at ratios of 7.5%, 12.5% and 20%, respectively. The PM produced was collected by a low pressure impactor（LPI）, and its composition was analyzed by SEM-EDS. The results show that the main composition of submicron particulate matter（PM₁） produced by Zhundong coal consists of Na, Mg, Ca, Fe and S, and Ca is the main composition of super-micron particulate matter(PM_1-10). While for rice husk, the PM₁ mainly consists of K, Cl, P, and PM_1-10 is dominated by Si. The amount of PM₁ in per unit mass was reduced during co-combustion when the ratio of rice husk was at 12.5% and 20%. And it was attributed to the interactions between the minerals in these two fuels and the vaporized elements（Na, Mg and K） released from the fuels. The PM_1-10 produced in per unit mass ash during co-combustion is almost equal to the value calculated from the two fuels when they combusted alone, and its amount decreases as the ratio of rice husk increases.