Using aluminum chloride, aluminite powders and butyl titanate as raw materials, alumina- aluminum titanate fiber was prepared by sol-gel method at 1200°C. The influences of the holding time on the aspect ratio, the bulk density, the thermal conductivity coefficient and the heating linear shrinkage of the fiber were studied systemically. The results show that the holding time has an important effect on the properties of the fiber. With the increase of the holding time from 0 h to 3 h, the aspect ratio of the fiber decreases from 870 to 210 and the bulk density of the fiber adds from 352 Kg•m-3 to 432 Kg•m-3. Furthermore, the thermal conductivity coefficient of the fiber keeps rising from 0.162 W•m-1•K-1 to 0.199 W•m-1•K-1 and the heating linear shrinkage of the fiber decreases from 2% to 1.82%.