To study chemical constituents from the flowers of Rhododendron pachypodum Balf.f.et W.W.Sm and their anti-inflammatory activities.Systematic separation methods (silica gel column chromatography,gel Sephadex LH-20 column chromatography,semi-preparative liquid chromatography) were used for the separation and purification of the ethyl acetate extract phase of R. pachypodum,and then the identification of compounds by modern spectroscopic methods,such as ¹H NMR,¹³C NMR,MS.The anti-inflammatory activities of compounds were evaluated by LPS induced RAW 264.7 inflammatory cell model.Twenty six compounds were isolated from the EtOAc extracts of the flowers of this plant and identified as grayanotoxin I (1), grayanotoxin II (2),pieristoxin S (3),dehydrovomifoliol (4),megastigm-5-en-3,9-diol (5),vomifoliol (6),5,6-epoxy-3-hydroxy-7-megastigmen-9-one (7),hydroxy-3-oxo-α-ionol (8),geranyllinalool (9),negunfurol (10),2,6,10-trimethyldodeca-6,11-diene-2,3,10-triol (11),9,10-dihydroxy-6,10-dimethylundec-5-en-2-one (12),(2Z)-2,6-dimethyl-2,7-octadiene-1,6-diol (13),medioresinol (14),pinoresinol (15),4-O-metbylcedrusin (16),naringenin (17),6,8-di-C-methyldihydrokaempferol (18),noreugenin (19),dihydroconiferyl alcohol (20),mycophenolic methyl ester (21),methyl orsellinate (22),scopoletin (23),salicyl alcohol (24),p-methoxyphebylacetic acid (25),and 5-methylbenzene-1,3-diol (26).Compound 13,16 and 18 showed potential inhibitory activity on NO production.Compound 16 showed significant activity,the IC₅₀ value of compound 16 was 33.5±1.5 μmol/L.