Abstract: The experiment studied the influences of different particle size components of corn stalk on its pore structure. The particle size distribution of corn stalk was measured by laser particle analyzer（LPA）, and the pore structure between corn stalk particles was measured by mercury intrusion porosimeter（MIP）. The experimental results showed that the pore ratio of the discontinuously graded particles was similar, but the peak value of pore distribution moved from 21 μm to 65 μm with the increase of particle content when the particle size was below 75 μm, therefore the peak value of pore distribution was 32 μm for continuously graded particles, when the coarse particle size（200～300 μm） increased, it showed that the maximum pore peak value would increase twice. The continuously graded particles had a double specific surface area than that of discontinuously. The experimental results provide reference value for the application of corn stalk powder.