Copper doped TiO2 prepared by the sol-gel method was used to enhance the performance of a photocatalytic degradation reaction. The optimum mol ratio of Cu to TiO2 was also analyzed and measured. As determined by XRD, FESEM, and Jade analysis, Cu doped TiO2 with a mol ratio of 1.0%, 1.5%, 2.0%, and 1.0% has better characteristics than German P25 TiO2, with grain sizes of 20-50 nm. In particular, 1.5% Cu doped TiO2 with a fine grain size had the highest and finest degree of crystallinity of TiO2 according to its XRD peak, and the reunion phenomenon was the weakest among all the Cu-TiO2. Combined with the Cu doping structure, micro stress changes, as well as the performance of the degradation of nitrobenzenes (NBs), the optimum mol ratio of Cu doped with TiO2 was 1.5%. With light degradation of NBs using 1.5% Cu-TiO2 for 180 min, the removal efficiency was twice as high as Germany P25 TiO2. The photocatalytic degradation reaction of NBs by Cu-TiO2 followed first order kinetics. Synthetically, FESEM, ESD, and the degradation of NBs performance confirmed that the optimal formula of CuxTi(1-x)O2 for the degradation of NBs is Cu0.018 3Ti0.981 7O2. Based on the varying concentrations of C and N elements in the solution, the intermediate reaction of NB degradation by CuxTi(1-x)O2 included the processes of benzene ring mineralization into CO2 and NO2- bond rupture.