$alpha$-Al2O3-15m/o ZrO2 powder was prepared by a sol-gel method from boehmite and zirconium acetate. The transformation temperature of boehmite to $alpha$-Al2O3 in the system Al2O3-ZrO2 was increased due to the coupled crystallization. On the other hand, the transformation temperature from boehmite to $alpha$-Al2O3-15m/o ZrO2 could be prepared at 110$0^{circ}C$ for 100min. The specific surface area of the product of $alpha$-Al2O3-15m/o ZrO2 was 13.2$m^2$/g.