Abstract: Aim To study the explosions induced by combustible dust and vapor cloud. Methods The experiment system was developed. Aluminum powder and pentane were taken as examples, and explosions of dust and vapor cloud induced by combustion under the weak ignition condition were studied. Results The combustion, explosion and detonation process was performed with the experimental set up and the pressure histories and flame signals were detected. Conclusion The experimental set up is practical, and the explosion process induced by week ignition may be divided into induction period, formation period, development period and detonation period.