Al ultra-fine grains are prepared by dry roller vibration milling at room temperature. After the ultrasonic hydrolyzing, the Al powders are milled for 2 h, 4 h and 8 h, separately, becoming the colloidal Al(OH)3. After the hydrolyzing production are dried, grinded, calcined, the flaky -Al2O3 nano-particles are obtained, and the particles sizes are in the range from 30 to 50 nm. By X ray diffraction (XRD) analysis method and transmission electron microscope (TEM), we analyze the energy conversion of solid particles in the vibration milling, and study the relation between the structure evolvement of solid particles and mechano-chemical reaction, in order to ascertain ideal milling time. The research results indicate that the solid particles under the action of mechanical force generate a mass of deformation and dislocation flaws and the material is in metastable high-energy state, which is favorable for inducing mechano-chemical reaction. In certain conditions, the surface energy of crystalloid, strain and dislocation energy could be mutually converted. The odds of lattice distortion and dislocation are maximal for the 2 h-milled Al powders, so the material shows a higher chemical reaction activation. On the ultrasonic agitation, the energy is fully released from the material interior, then Al(OH)3 nano-particles are prepared in a short time.