MeOH extract of Cuscuta chinensis seeds was fractionated with n-hexane, EtOAc and BuOH successively, and antioxidant activities were tested for all fractions using DPPH free radical scavenging method. In the tested fractions, EtOAc fraction showed high antioxidant activity (EC50, 50 μg) From the EtOAc fraction, five compounds have been isolated. On the basis of spectral data, these compounds were identified as β-sitosterol, methyl 4-hydroxy-3,5-dimethoxycinnamate, β-sitosterol-3-O-β-D-glucopyranoside, caffeic acid, quercetin, kaempferol and calycopteretin. Among these compounds, β-sitosterol and β-sitosterol-3-O-β-D-glucopyranoside showed no antioxidant activity. EC50 values of methyl 4-hydroxy-3,5-dimethoxycinnamate, caffeic acid, quercetin, kaempferol and calycopteretin were 0.6, 8, 19, 17 and 12 μg, respectively.