Contrast degradation experiments between ethanol and polyvinyl alcohol (PVA) were conducted during H2O2, UV/H2O2, Fenton, and Photo-Fenton processes in this study. UV/VIS spectra showed. that complexes between Fe(Ⅲ) and organics were easily formed and degraded within reaction time. Compared with the degradation of complex, hydroxyl radicals acted weakly in Fenton or Photo-Fenton process. Hydroxyl radicals involved in Photo-Fenton process were deemed to be generated from the split decomposition of H2O2, photolysis of Fe3+/aq, and degradation of hydrated Fe(Ⅳ)-complex but not traditional Fenton reaction. Experimental evidence to support this point was presented in this paper.