Owing to its industrial importance, various techniques for the preparation of thermostable active alumina have been developed. These techniques can be divided into two categories. One is to stabilize transitional alumina by the addition of foreign oxides such as BaO, La2O3, SiO2 and so on[1～3]. In this category, the stabilization of alumina comes about by the formation of thermostable compounds on the alumina surface or by the transformation of alumina into other materials such as BaAl12O19 and LaAl11O19. The other category is to improve the thermostability of alumina by modifying its morphology during its preparation, instead of incorporating additives. For example, Ishikawa et al[4] prepared thermally stabilized transitional alumina by fume pyrolysis of boehmite sols. Even after calcination at 1200 ℃ for 30 h, the alumina still possesses a surface area as high as 50 m2/g. This was ascribed to the suppression of transformation to α-phase from transition Al2O3, owing to that the alumina particles being of a crude structure and assembled by fibrils. Tsutsumi et al[5] reported a multi-layered alumina film, with a surface area of 100 m2/g after calcination at 1300～1500 ℃, prepared by using a multi-bilayer cast film of a double-chain ammonium amphiphile as a molecular template.rn