Nanosized aluminum hydroxide was prepared by carbonation in a hypergravity rotating packed bed（RPB）reactor using sodium meta-aluminate and carbon dioxide as source materials.Characterization of XRD，TEM，TG-DSC and particle size distribution indicated that the as-prepared product was bayerite with hexagonal-plate shape and particle size of less than 100 nm，which also exhibited uniform morphology，narrow particle size distribution and good dispersibility.The optimum synthesis conditions were obtained.The experimental results showed that the preparation of hexagonal-plate-shaped aluminum hydroxide by RPB is technically feasible due to its simplicity and reproducibility.