1. The oxidation of bilirubin by oxygen in alkaline solution was rapidly performed with high pH value, and the diazo reaction was positive for a while after the disappearance of the absorption maximum of bilirubin. 2. The absorption maximum of propentdyopent product displayed at 264 mn, that of pentdyopent product displayed at 523 mμ and that of bilifuscin displayed at 270 mμ in aqueous sclution. 3. Bilirubin turned into biliverdin at first, and then it turned into bilifuscin through pentdyopent product on the oxidation process. 4. Bilirubin and biliverdin were identified by chromatography in alkaline solution of bilirubin after the disappearance of it's absorption maximum and the display of negative diazo reaction. 5. The oxidation process of bilirubin in the sun light was same to that in the air, but the decomposition velocity of the former was more rapid than that of the latter. 6. Bilifuscin was separated, by the difference of cross-combination, in order of water soluble, chloroform soluble and methanol soluble one.