The structural change of gibbsite induced by dry grinding has been investigated by means of BET analysis, SEM observation, XRD, MAS/NMR spectroscopy and TG-DTA. The crystalline structure of gibbsite changes into a disordered one with the progress of grinding and subsequent RDF analysis of ground gibbsite samples suggests the structural variation in the local atomic arrangement around aluminum. MAS/NMR measurement also supports this change and indicates the formation of a tetra- and penta-coordinated aluminum at the expense of parent octahedral ones. Low temperature dehydroxylation reaction and new exothermic peaks at about 800 and 1000°C of ground samples were detected in TG-DTA.