A novel synthesis process has been developed for producing high purity nonagglomerate nano platelike α-Al 2 O 3 particles. The process mainly utilizes a seed-effect of fine α-Al 2 O 3 grains, worn from the milling mediums and uniformly mixed with the hydrous alumina during grinding, and also utilizes ZnF 2 additive to reduce the transformation temperature and modify the alumina particle shape. The aspect ratio and the average size of Al 2 O 3 particles prepared at 900 o C for 1<space>h is 2-4 and 40<space>nm, respectively.