Abstract: The flaky α-alumina is prepared by high-temperature solid phase method using aluminum hydroxide with different particle sizes as raw material.The products were characterized by laser particle size analyzer，scanning electron microscopy， and X-ray diffraction，and the optimum preparation conditions were determined.Result showed that flaky α-alumina under the optimum preparation conditions had the particle size about 20 μm，diameter to thickness ratio of（5~8）∶1，and most of hexagonal flakes.And the degree of overlap of adsorption-desorption isotherms to characterize flaky alumina was first used in its preparation.

Key words: flaky alumina, high-temperature solid phase method, adsorption-desorption isotherms