A　novel　Ti-doped　Sm-Mn　mixed　oxide　(TiSmMnOx)　was　first　designed　for　the　selective　catalytic　reduction　(SCR)　of　NOx　with　NH3　at　a　low　temperature.　The　TiSmMnOx　catalyst　exhibited　a　superior　catalytic　performance,　in　which　NOx　conversion　higher　than　80%　and　N2　selectivity　above　90%　could　be　achieved　in　a　wide-operating　temperature　window　(60-225　°C).　Specially,　the　catalyst　also　showed　high　durability　against　the　large　space　velocity　and　excellent　SO2/H2O　resistance.　Ti　incorporation　can　efficiently　inhibit　MnOx　crystallization　and　tune　the　MnOx　phase　during　calcination　at　a　high　temperature.　Subsequently,　a　high　specific　surface　area　as　well　as　an　increased　amount　of　acid　sites　on　the　TiSmMnOx　catalysts　were　produced.　Further,　the　reducibility　of　the　Sm-doped　MnOx　catalyst　was　modulated,　facilitating　NO　oxidation　and　inhibiting　NH3　nonselective　oxidation.　Consequently,　a　superior　SCR　activity　was　achieved　at　a　low　temperature　and　the　operating　temperature　window　of　the　TiSmMnOx　catalyst　was　significantly　widened.　These　findings　may　provide　new　insights　into　the　reasonable　design　and　development　of　the　new　non-vanadium　catalysts　with　a　high　NH3-SCR　activity　for　industrial　application.　Copyright　©　2020　American　Chemical　Society.