SAPO-34 was prepared with a mixture of three templates containing triethylamine, tetraethylammonium hydroxide, and morpholine, which leads to unique properties for support and production cost reduction. Meanwhile, Cu/SAPO-34, Fe/SAPO-34, and Cu-Fe/SAPO-34 were prepared through the ion-exchanged method in aqueous solution and used for selective catalytic reduction (SCR) of NO_x with NH₃. The physical structure and original crystal of SAPO-34 are maintained in the catalysts. Cu-Fe/SAPO-34 catalysts exhibit high NO_x conversion in a broad temperature window, even in the presence of H₂O. The physicochemical properties of synthesized samples were further characterized by various methods, including XRD, FE-SEM, EDS, N₂ adsorption-desorption isotherms, UV-Vis-DRS spectroscopy, NH₃-TPD, H₂-TPR, and EPR. The best catalyst, 3Cu-1Fe/SAPO-34 exhibited high NO_x conversion (> 90%) in a wide temperature window of 250–600 °C, even in the presence of H₂O. In comparison with mono-metallic samples, the 3Cu-1Fe/SAPO-34 catalyst had more isolated Cu²⁺ ions and additional oligomeric Fe³⁺ active sites, which mainly contributed to the higher capacity of NH₃ and NO_x adsorption by the enhancement of the number of acid sites as well as its greater reducibility. Therefore, this synergistic effect between iron and copper in the 3Cu-1Fe/SAPO-34 catalyst prompted higher catalytic performance in more extensive temperature as well as hydrothermal stability after iron incorporation.