In this study, the explosion characteristic of aluminium powders have been investigated as a function of particle size using by a 20 L dust explosion apparatus (K$ddot{u}$hner). The tested aluminium particle sizes were the volume mean diameter of 16, 33 and $88{mu}m$. The lower explosion limit increases gradually with the increasing of dust particle diameter, respectively 40, 60, $125g/m^3$ in mean diameter of 16, 33 and $88{mu}m$. Also the increase in particle size for each aluminum dusts was found to cause an decrease in explosion pressure and Kst of dust explosion index, and a increase in the lower explosion concentration. Research results may have important implications for aluminum powders utilization and safety operation.