Abstract: The current research included a study of photocatalytic degradation of polyvinyl alcohol (PVA) films prepared by the pouring method after adding different weight ratios of nickel complex to a leucine derivative (0.4%, 0.2%, 0.1%, 0.05%, 0.025%) with thickness of 75±5 μm. The effect of the additive ratio on the photocatalytic degradation speed of polymeric films relative to pure films before and after exposure to the source of ultraviolet was studied, which showed the highest absorption at the wavelength of 356 nm with irradiation times starting from 25-100 hrs. The photocatalytic degradation process has been monitored by using the UV-VIS spectrophotometer to calculate the degradation rate constant (Kd), the infrared (FT-IR) device to calculate the growth coefficient of carbonyl (ICO) and hydroxyl (IOH) groups and the viscosity technique to follow the change in the viscosity-average molecular weight. It was found through FT-IR and UV-Vis that the degradation rate constant and growth coefficients of carbonyl and hydroxyl were inversely proportional with the concentration of the added nickel complex and the irradiation time. The results of viscosity measurements obtained from the calculation of the degradation degree and the numerical rate of chain (S) scission showed that increasing concentrationS of the added nickel complex reduces the degradation of the polymer molecular weight. Thus it is considered a stabilizer for photocatalytic degradation.