Characteristics of photosensitization and dark reaction of hypericin (HYP) are studied in DMSO homogeneous system. Rate constant ratio of HYP of generating O,2,1, to O,2,·-, isdetermined as 0.057 and rate constant ratio of generating O,2,1, to anionradical of HYP (HYP,·-,) is determined as 1.25. It is also found that in existence of cysteine,HYP produce O,2,·-, through thermochemica reaction,but the amount of ,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42651273&type=,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42651275&type=,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42651274&type=, is lower than that produced by HA. In TX-100 micellarheterogeneous system,amounts of produced ,1,O,2, and ,•,OH through photosensitization of HYP and HA are compared and it is found that the amount of generated ,1,O,2, is similar to each other,but amount of produced OH of HYP is higher than that of HA.