A series of CeO2-La2O3 supported ruthenium catalysts were prepared by co-precipitation method and the as-obtained samples were characterized by N-2 physisorption, X-ray diffraction, CO chemisorption, H-2-TPR, H-2-TPD and XPS. The activity test shows that ammonia concentration of the catalyst with 10% La is 13.9% at 10 MPa, 10,000 h(-1), 450 A degrees C, which is 17% higher than that of Ru/CeO2. La doping can improve the activity of Ru-ceria catalyst for ammonia synthesis by facilitating the reduction of oxygen which subsists in the cerium oxide surface. In addition, it can be realized that the test of catalyst stability proves the stability performance of Ru/CeO2-La2O3 catalyst within the reaction time of 55 h.