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 Fe-aq(3+), and degradation of hydrated Fe(IV)-complex but not traditional Fenton reaction. Experimental evidence to support this point was presented in this paper.