Al2O3-doped ZnO ceramics were prepared via chemical co-precipitation processing. Zinc acetate, ammonia and Al2O3 powders are used as starting materials. Scanning electron microscopy (SEM) observations reveal that the doping of Al2O3 has an obvious influence on the microstructure of ZnO ceramics. Ordinary cold pressing and cold isostatic pressing (CIP) were used to prepare green compacts. The thermal conductivity and electrical conductivity of the Al2O3-doped ZnO ceramics were measured as a function of the testing temperature (0-900oC). Doping of Al2O3 is beneficial to improve thermoelectric (TE) properties of ZnO ceramics. CIP can also improve TE properties of Al2O3-doped ZnO ceramics.