Abstract: The particle size and concentration of coal dust is very important during combustion explosion.The explosion danger is increased rapidly with the size reduction.Using volatile content between 15% and 30% and ash content less than 30%,the coal dust explosion limit is decreased with the volatile content increasing.Through the experiment,while different concentrations of coal powder are added to the fuel chamber,the mixture detonation pressure and detonation velocity are not the same.The less the addition of coal powder is,the lower the detonation pressure and velocity are,and the mixture is in deflagration.When the dust concentration is 276g/m³ or 368g/m³,stable detonation appears during coal dust explosion.The detonation pressure is increased as the coal dust particle size is decreased,and a stable detonation process is occurred with coal dust particle size of 45 to 75 μm.Therefore,studying the experimental combustion and explosion characteristics is very reasonable under such conditions.