Achieving the selective oxidation of hazardous nitrogen-containing volatile organic compounds to the harmless molecular N-2 still remains a big challenge. Here, we present the synthesis of CuO catalysts supported by ZSM-5 with different SiO2/Al2O3 ratios through the impregnation method. With the X-ray diffraction, hydrogen temperature-programmed reduction, temperature-programmed desorption of NH3, and X-ray photoelectron spectroscopy characterization of the catalysts, the influences of both the SiO2/Al2O3 ratio in ZSM-5 and the amount of CuO loadings on the catalytic oxidation activity and N-2 selectivity over CuO/ZSM-5 catalysts for diethylamine oxidation were investigated in detail. As the SiO2/Al2O3 ratio of ZSM-5 decreases from 360 to 18, the catalytic oxidation activity of diethylamine over the CuO/ZSM-5 catalyst increases (T-98 decreases), and the selectivity of N-2 generation obviously increases. Among them, the 6CuO/ZSM-5-18 catalyst shows the best catalytic performance, of which T-98 for diethylamine oxidation is 240 degrees C, and the selectivity for N-2 is exceeding 95.5% at 400 degrees C. Moreover, the 6CuO/ZSM-5-18 catalyst gives the widest temperature window (Delta T = 160 degrees C) for N-2 selectivity over 95%. The surface acidity of the CuO/ZSM-5 catalyst increases when the SiO2/Al2O3 ratio in ZSM-5 decreases, so that the amount of easily reducible CuO species increases. The CuO species improve the catalytic oxidation activity, and the increasing amount of surface acid sites and strong acid sites on the support are favorable for the activation of diethylamine and the formation of N-2. Thus, it could be inferred that the cooperative catalysis of highly dispersed CuO with surface acid sites in the catalyst is beneficial to the selective catalytic oxidation of diethylamine.