In order to study the peroxidation reaction of phosphatidylcholine and liposome induced by UV and the protection of cholesterol to phosphatidylcholine and liposome, predominantly unilamellar vesicles (ULVs) prepared by L-α-phosphatidylcholine were used as an alternate biological model. Phosphatidylcholine and liposome made by 20μmol of L-α-phosphatidylcholine with or without cholesterol were irradiated by 254 nm UV ray. Radiation induced peroxidation in phosphatidylcholine and liposome was measured spectrophotometrically by thiobarbituric acid (TBA) reaction. The results show that, the peroxidation of phosphatidylcholine and liposome increased with the UV irradiation dose. The liposome was more sensitive to UV radiation than phosphatidylcholine. Cholestrol significantly prevented Liposomal peroxidation, but had no effect on phosphatidylcholine peroxidation. The peroxidation of phosphatidylcholine and liposome is apparently related to the concentration and dose, and cholesterol can only protect liposome.