A series of Fex–Cu4/ZSM-5 catalysts with fixed Cu content and variable Fe loading amounts were synthesized by an improved incipient-wetness-impregnation method, and their catalytic performances were tested for selective catalytic reduction (SCR) of NO with ammonia as reductant. The catalysts were characterized by means of XRD, BET, SEM, TEM, FT-IR, UV–vis DRS, UV-Raman, NH3-TPD, Py-IR, H2-TPR and XPS. The results indicated that the high activities of Fex–Cu4/ZSM-5 could be attributed to the formation of Fe–Cu nanocomposites with high dispersion. The interaction between the iron and copper species in the Fe–Cu nanocomposites leads to the change of electronic properties, the stronger redox ability and more acid sites over catalyst surface for Fex–Cu4/ZSM-5 comparing with Cu4/ZSM-5. Thus, the addition of iron to Cu4/ZSM-5 catalyst improved its catalytic performance, and Fe4–Cu4/ZSM-5 catalyst exhibited the high NO conversion (>90%) among the wide temperature range (200–475°C).