Core-shell nano-Al2O3-coated ZrO2 materials were prepared via a liquid co-deposition method using ZrO2 as cores. Surface of ZrO2 was modified by silane coupling agent. The mechanism of A-151[CH2=CH-Si-(OC2H5)3] was studied under the condition of HAc. The composite powders were characterized by FT-IR, TEM, EDS and SEM. TEM observation confirmed that amorphous Al2O3 layer deposited on the surface of ZrO2 and the thickness of the Al2O3 coating ranged from 5 to 10 nm. After sintered at 1650°C for 10 h, the size distribution narrowed down and the compactness of composite sintered body was better in comparison with pure zirconia.