The hemoglobin site-specifically modified with ferulic acid (FA-Hb) has been synthesized in order to analyze the autoxidation of FA-Hb. The effect on the characteristic absorption and the oxygen saturation curve of FA-Hb was investigated by UV spectro-photometry and oxygen analyzer. Furthermore, the autoxidation rate of Hb and FA-Hb was discussed, with or without nitrogen sodium, xanthine- xanthine oxidase mediated in the system. The results showed that the heme structure of FA-Hb is the same as the hemoglobin. It also demonstrated that the oxygen carrying activity of them is same. But, the autoxidation rate of FA-Hb is much lower than Hb in different systems.