Abstract: The scavenging ability on ROS and products of lipid peroxidation of red pigment from purple sweet potato was analysed by means of colorimetry (spectrophotometry) , chemiluminescence, fluorospectrophotometry, in models for generation of superoxide anion, hydroxyl radicals malonaldehyde (MDA) . The results showed that the red pigment had certain scavenging effects on superoxide anion produced by pyrogallol autoxidation system, but lower than L-Ascorbic acid (VC) , and the scavenging effects determined by chemiluminescence was stronger than colorimetry. The pigment had scavenging effects on hydroxyl free radical produced by Fenton reaction, and the effects determined by chemiluminescence (stronger than VC) was the strongest, next fluorescence (stronger slightly than VC) , final colorimetry (lower evidently than VCat high concentrations) . The pigment also had inhibitory action on generation of MDA, the production of lipid peroxidation induced by Fe2+-H2O2on rat liver tissue homogenates in vitro, and the action determined by TBA fluorospectrophotometry (lowerer slightly than VC) was stronger than TBA colorimetry (lower evidently than VCat high concentrations) .Compared with colorimetry, chemiluminescence and fluorescence had high sensitivity and strong selectivity, and overcome the interference from spectral absorption of the pigment at the visible light on the test results.