Abstract: Using SSZ-39 as support, Cu-Mn/SSZ-39 zeolite catalysts with different Cu/Mn mole ratio were prepared by ion-exchange method for selective catalytic reduction of NO by NH3 (NH3-SCR). The structures, morphologies and surface acidities of the catalysts were characterized by XRD, SEM, N2 adsorption-desorption , NH3-TPD, H2-TPR ,XPS and ICP techniques. The results show that Cu2 provides the major active sites. The catalysts exchanged with Cu2 have the good catalytic activities and N2 selectivities. The moderate exchange of Mn2 /3 increases the concentration of acid sites, especially the weak Lewis acid sites. The Cu-Mn/SSZ-39 catalysts show the good low temperature NH3-SCR activities and hydrothermal stability. When the mole ratio of Cu:Mn is 1:0.6, Cu-Mn(0.6)/SSZ-39 has the excellent low light-off temperature (T50 is 125 ℃), wide temperature window from 184 ℃ to 433 ℃, and the N2 selectivity reaches above 90% at below 450 ℃. After hydrothermal aging, the initial original crystal structure, morphology and NH3-SCR activity of Cu-Mn(0.6)/SSZ-39-A are well maintained, showing a good hydrothermal stability.