The regularity of NO

x

emission performance along with coal sort

excess air ratio and temperature variation during combustion of different particle size for pulverized coal in onedimensional hotstate experimental furnace has been respectively studied. Results of study show that there is a critical value of pulverized coal particle size existing between NO

x

emission concentration and the said particle size. When the said particle size to be smaller than the said critical value

the NO

x

emission concentration to be reduced along with reduction of the particle size; when the particle size to be greater than the said critical value

the NO

x

emission concentration to be increased along with the reduction of the particle size. After the pulverized coal being ultrafinely subdivided

the NO

x

emission concentration for brown coal and bituminous coal is obviously reduced

but for lean coal and blind coal

the variation of NO

x

emission concentration to be very small.