To investigate the chemical constituents from Corydalis impatiens,various column chromatography techniques,including silica gel,Sephadex LH-20,ODS and semi-preparative HPLC were used.The structures were identified by NMR,MS,physicochemical properties and/or comparison with literature data.As a result,twenty known phenolic compounds were isolated and identified as (3S)-5-guaiacyl-3-hydroxypentanoic methyl ester (1),8-C-p-hydroxybenzylquercetin (2),8-C-p-hydroxybenzylkaempferol (3),6-C-p-hydroxybenzylquercetin (4),quercetin (5),kaempferol (6),chrysoeriol (7),1,7-dihydroxy-3,8-dimethoxyxanthone (8),1-hydroxy-2,3,5-trimethoxyxanthone (9),1-hydroxy-2,3,4,6-tetramethoxyxanthone (10),p-hydroxyphenylferulate (11),esculetin (12),4,4′-dihydroxydibenzyl ether (13),3-methoxy-4-hydroxy-phenylethanol (14),3,4-dihydroxyphenylethanol (15),4-hydroxyphenylethanol (16),p-hydroxybenzylethyl ether (17),p-hydroxyphenylmethanol (18),1,2,4-trihydroxybenzene (19),1,2-benzenediol (20).Compound 1 is a new natural compound,2-4 and 7-20 were obtained from genus Corydalis for the first time,and 5 and 6 were isolated from this plant for the first time.All of the compounds obtained were evaluated in vitro by MTT assay against human hepatic cell line HepG2 and SMMC-7721.Compounds 2 and 3 exhibited moderate inhibition on HepG2 with IC₅₀ values of 16.8 and 19.2 μmol/L,respectively.