High-purity alumina ceramics were prepared by sintering at low temperature, using rare earth oxide Y2O3 and Tm2O3 as sintering aids. Adding the mixture of Y2O3 and Tm2O3 in the alumina powders can effectively improve the sintering ability and mechanical properties. The mixture, Y2O3+Tm2O3, can restrain the grains growth, fine the grain size, make the grain uniform and finally help to form compact structure. The transgranular fracture was the main fracture mode. It was found the relative density of alumina ceramics with 0.3wt% Y2O3 and Tm2O3, sintered at 1620°C for 3hrs, can be over 99.2% and the strength, toughness and microhardness reach 533.1MPa, 4.9MPa⋅m1/2 and 17.2GPa, respectively.