Abstract: In order to reveal the danger of sulphur dust explosion，the parameters of explosive characteristics of the sulphur dust with different particle sizes were tested and assessed through a Hartmann tube explosion test unit and a 20 L sphere explosion test unit under the normal temperature and pressure.The minimum ignition energy（MIE），minimum explosion concentration（MEC），and the explosion index of sulphur dust with different particle sizes were obtained.The risk degree of explosion was graded according to the test results.Results showed the MIE of sulphur dusts with the particle sizes of 70~ 850 μm was 0.144~125 mJ，and it will decrease with the decrease of particle size；the MEC of sulphur dusts with the particle sizes of 45~375 μm was 15~20 g/m3， and it will decrease with the decrease of particle size；and the explosion index of sulphur dusts with the particle sizes of 45~375 μm was 34.46~39.87 MPa·m/s，and it will increase with the decrease of particle size and its dust explosion risk class was St3.

Key words: sulphur, dust explosion, minimum ignition energy（MIE）, minimum explosion concentration（MEC）, explosion index