The Mg,Al,Alkaline-earth mixed oxides were synthesized by co-precipitation of two mixed solutions and then loaded with Ru to get the Ru-based catalyst.X-ray diffraction,CO2-adsorption,N2 physical-adsorption and SEM were introduced to characterize the phase,basicity,area,and configuration of the surface of the mixed oxide.The ammonia synthesis experiment was carried out under the fluxin of 3H2/1N2,with the velocity 2100 mL/h and pressure 0.2 MPa.The activity test shows that the catalyst supported on mixed oxide has far more better activity than those supported on single oxide.It can be concluded from the result of the characterization and activity test that the activity of the catalyst was mainly affected by the basicity of the surface rather than the surface areas.