Flow injection chemiluminescence analysis was used to determine the antioxidation activity of extract from Morinda officinalis How. The determination was based on the inhibition effect of Morinda officinalis How extraction in the chemiluminescence reaction of luminol - H2O2-CuSO4 system, and vitamin C was used as positive control. It was showed that Morinda officinalis How original liquid has obvious anti-radical activity. Spectroscopy was applied to determine the inhibition ratio of Morinda officinalis How extraction for the superoxide anion and hydroxy radicals in the special system. It was shown that the extraction from Morinda officinalis How could obviously scavenge superoxide anion and hydroxy radicals. It is suggested that the Chinese Medicine Morinda Officinalis How is a potential antioxidation activity medicine.