The total saponins, total flavonoids and total proteins were extracted from Ophiopogon japonicus. The antioxidant activity of three extracts were investigated by DPPH assay. Ascorbic acid, thiourea and catechins were used as posititive control and IC50 value as the evaluating criterion of DPPH free radical scavenging capability. The results show that at the wavelength of 517 nm, the calibration curves showed good linearity in the range of 25.8~51.5 μg/mL of DPPH. The IC50 of antioxidants(ascorbic acid, thiourea and catechins) were 87.0，482.9 and 10.2 μg/mL respectively. The IC50 of the extracts from O. japonicus(total saponins, total flavonoids and total proteins) were 509.0，79.4 and 46.0 μg/mL. The strength in the order of IC50 was catechins﹥total proteins﹥total flavonoids﹥ascorbic acid﹥thiourea﹥total saponins. In addition, multi-cluster analysis show that total flavonoids, total proteins, ascorbic acid and catechins had a similar intensity of antioxidant activity, which sihgnifies that the total flavonoids and total proteins from O. japonicus had strong antioxidant activity.