A novel chemical method for preparing nanocrystalline alpha-Al2O3 powder has been developed in this study. The aluminum hydroxide precipitates were initially formed in a three-dimensional space network micro-area of the wet gel, and then the precursor was obtained after the wet gel was dried. The nanocrystalline alpha-Al2O3 powders were obtained after the precursor was calcined at 1100 degrees C. The precursor and as-calcined powders were characterized using TGA-DTA, XRD, and TEM. The alpha-Al2O3 powders calcined at 1100 degrees C for 2h are of narrow distribution, little agglomeration, and small particle size of similar to 51nm. The reason for the synthesis of the high-quality powders is explained.