A chemical investigation of the n-butanol fraction of the inner bark of Betula platyphylla led to the isolation of seven diarylhepanoids, (-)-centrolobol (1), aceroside VII (2), aceroside VIII (3), (3R)-1,7-bis-(4-hydroxyphenyl)-3-heptanol-3-O-[2,6-bis-O-(β-D-apiofuranosyl)-β-D-glucopyranoside (4), 1,7-bis-(4-hydroxyphenyl)-5-hepten-3-one (5), platyphyllone (6) and platyphylloside (7). The antifibrotic effects of these isolates were evaluated with HSC-T6 cells by assessing cell proliferation. Among them, compounds 1, 2, 5 and 6 significantly inhibited the proliferation of HSCs in a dose-dependent manner at concentrations from 10 µM to 100 µM. Compound 5 in particular dramatically decreased the collagen content and increased the Caspase-3/7 activity. Taken together, the antifibrotic activity of B. platyphylla and its constituents might suggest therapeutic potential against liver fibrosis.