Abstract: In order to control the emission of particulate matter( PM) from coal combustion,it is necessary to have a thorough understanding of the emission rule and formation mechanism of PM. During pulverized coal combustion,PM can be divided into three formation modes: coarse mode,fine mode,and ultrafine mode.Compared to the coarse mode,the fine mode particles account for a larger proportion,and affect human health and atmospheric environment due to their small sizes and enrichment characteristics.Besides,the systemic summary of formation mechanism and research progress on fine mode PM are relatively lacking,compared with that of ultrafine mode,and it is difficult to suppress the emission of the fine mode PM.In this paper,the formation mechanisms of fine mode PM( char fragmentation,mineral melt coalescence,exterior mineral fragmentation and ash shedding) as well as the main influencefactors were analyzed.The research progress of simulationwere discussed and the research emphasis in future was pointed out.The particle size distribution of PM in coal ash turns out to be the result of competition between the char fragmentation and mineral aggregation. The fragmentations results in the increase of amount and the decrease of particle size of fine mode PM,while mineral aggregation leads to the amount decrease of PM,which is conducive to the formation of coarse mode PM.The main factors affecting the formation of PM arepore structure,combustion mode and char particle size.With relatively higher porosity,char cenospheres are more likely to broken up into more fine mode PM than other chars.Both increasing temperature,oxygen content and decreasing particle size are helpful to the formation of PM,but the aggregation of ash particles at higher temperature may lead to the particle size distribution towards coarse mode PM.The simulation of coke combustion characteristics by fragmentation behavior is mainly divided as population balance model and percolative fragmentation model. On the basis of the formation mechanism and influencing factors of fine mode PM,the percolative model is more suitable for simulating the char fragmentation,which takes the porous char structure into account.Therefore,the combination of kinetics combustion model and percolative fragmentation model is the key for the accurate prediction on the ash particle size distribution,which is the next research focus.