A new monoterpene, (‐)‐10‐hydroxydihydroactinidiolide (1), along with two known monoterpenes, loliolide (2) and (+)‐isololiolide (3), three known megastigmanes, 3a‐hydroxy‐5β,6β‐epoxy‐β‐ionone (4), 3a‐hydroxy‐5a,6a‐epoxy‐β‐ionone (5), and (+)‐dehydrovomifoliol (6), an eudesmane‐type sesquiterpene, 4a‐hydroxy‐4β‐methyldihydrocostol (7), a monoterpene, 8‐hydroxycarvotanacetone (8), two flavonoids, chrysoeriol (9) and apigenin (10), and a phenylpropanoid, 3‐(4‐hydroxyphenyl)‐1‐propanol (11), were isolated from the whole plant of Achillea millefolium. The structure of compound 1 was identified according to spectroscopic data of HRMS and NMR, and its absolute configuration was assigned by 13C NMR calculations with DP4+ probability analyses and ECD calculations. The absolute configuration of compound 6 was determined by ECD calculations. Compounds 3, 6, 9 and 10 could dose‐dependently inhibited the NO release in LPS‐induced RAW267.4 cells.