Polyvinyl alcohol (PVA) bearing coumarin was synthesized by esterification between hydroxyl of PVA and 7-carboxylmethoxycoumarin, using 4-dimethylamiopryidine (DMAP) and dicyclohexylcarbodiimide (DCC) as catalysts. The double bond changes of solution and polymer film during the progress of photocrosslink and photocleavage were studied by UV-vis spectra and FT-IR, respectively. The results show that polyvinyl alcohol bearing coumarin has the property of photoreversible, the photocrosslink rate is 10 times greater than photocleavage rate in solution. In the polymer film state, the photocrosslink rate of double bond is improved with temperature and time increasing. The photocleavage rate in polymer film state is slower than that in solution, and higher temperature is always helpful for the photocleavage property.