The explosive process and explosive characteristics of superfine coal dust with four kinds of different particle diameters are studied.The change of industrial compositions and physical state of superfine coal dust are investigated.The effects of concentration and particle diameter of coal dust on the largest explosive pressure and the largest ascending rate of explosive pressure are analyzed.It is indicated by the experiment that with the decrease of particle diameter of coal dust

the amount of dirt produced by explosion falls down;and that the larger maximum explosive pressure

the larger maximum ascending rate of explosive pressure.