This study aims to study the constituents from the pericarp of Tamarindus indica Linn. and their antioxidant activity. Eighteen compounds were isolated from the acetone extract by chromatographic separation technology. On the basis of NMR spectroscopic data,they were identifeid as luteolin (1),7,3′,4′-trihydroxyflavone (2),apigenin (3),7,4′-dihydroxyflavone (4),geraldone (5),astragalin (6),quercetin (7),kaempferol (8),acacetin (9),eriodictyol (10),naringenin (11),butin (12),dihydrokaempferol (13),3′,5,5′,7-tetrahydroxyflavanone (14),5,6,7,4′-tetrahydroxyflavanone (15),3,3′,5,5′,7-pentahydroxyflavanone (16),catechin (17),epicatechin (18).Ten of them (2,4-6,9,11,13-16) were isolated from this genus for the first time.By ORAC assay in vitro,it was found that four extracts and nine compounds (1,2,7-10,12,13,17) exhibited antioxidant activity.