The effect of Ultra-violet light on the structure and motion of the polyvinyl alcohol(PVA) chains was studied by 1H NMR, spin-lattice relaxation and IR spectroscopy. The results indicated that with the increase of irradiation time, the intensity of the polymer hydroxyl proton peaks decreased and finally vanished, which suggested the self-condensation between the hydroxyl groups proceeded. No methyl proton peaks appeared in the spectra after irradiation shows that there is no cleavage of polymer chain. The longer the irradiation time is, the wider the proton peak of the residual water of the solvent is and it shifted toward low field. This result implies that the hydrogen bonds formed between the polymer and the residual water. The absorption peak of hydroxyl group of the polymer moves toward the lower wave number in the IR spectrum that showed the existence of the hydrogen bonds between the PVA macromolecules.