Lanthanide　(La,　Ce,　Nd,　Gd,　Tb,　Ho　or　Lu)-doped　Cu-SAPO-18　samples　were　prepared　using　the　ion-exchange　method.　Physicochemical　properties　of　the　samples　were　systematically　characterized　by　a　number　of　analytical　techniques,　and　the　effects　of　lanthanide　doping　on　catalytic　activity　and　hydrothermal　stability　of　the　Cu-SAPO-18　catalysts　for　the　NH3-SCR　reaction　were　examined.　It　is　shown　that　the　doping　of　lanthanide　elements　could　affect　the　interaction　between　the　active　components　(copper　ions)　and　the　AEI-structured　SAPO-18　support.　The　inclusion　of　some　lanthanides　significantly　slowed　down　hydrolysis　of　the　catalyst　during　hydrothermal　aging　treatment　process,　leading　to　an　enhanced　catalytic　activity　at　both　low　and　high　temperatures　and　hydrothermal　stability.　In　particular,　Ce　doping　promoted　the　Cu2+　ions　to　migrate　to　the　energetically　favorable　sites　for　enhancement　in　catalytic　activity,　whereas　the　other　lanthanide　ions　exerted　little　or　an　opposite　effect　on　the　migration　of　Cu2+　ions.　Additionally,　Ce　doping　could　improve　hydrothermal　stability　of　the　Cu-SAPO-18　catalyst　by　weakening　hydrolysis　of　the　catalyst　during　the　hydrothermal　aging　treatment　process.　Ce　doping　increased　the　catalytic　activity　of　Cu-SAPO-18　at　low　and　high　temperatures,　which　was　attributed　to　modifications　of　the　redox　and/or　isolated　Cu2+　active　centers.