The　Pr-doped　ceria　supported　ruthenium　catalyst　Ru/CeO2-PrO2　for　ammonia　synthesis　was　prepared　by　a　redox　co-precipitation　method.　The　obtained　catalyst　samples　were　characterized　by　N-2　physisorption,　X-ray　diffraction,　H-2　temperature-programmed　reduction,　CO　chemisorption,　temperature-programmed　desorption　of　nitrogen,　field-emission　scanning　electron　microscopy,　high　resolution　transmission　electron　microscopy,　and　X-ray　photoelectron　spectroscopy.　The　effects　of　Pr　doping　amount　on　the　microstructure　and　catalytic　properties　of　Ru/CeO2-PrO2　were　investigated.　The　results　showed　that　the　composite　oxide　created　form　Pr-doped　ceria　has　some　influence　on　the　Ru　dispersion　and　surface　texture.　The　activity　test　showed　that　the　ammonia　synthesis　transformation　frequency　over　the　Ru/CeO2-PrO2　catalyst　with　4%　Pr　was　12.13　x　10(-2)　s(-1)　at　10　MPa,　10000　h(-1),　and　425　degrees　C,　which　was　58%　higher　than　that　of　Ru/CeO2.　The　improvement　of　electrical　conductivity　performance　is　the　key　factor　for　the　higher　catalytic　activity.