Abstract: Piper hancei Maxim, Family Piperaceae, has been used in Chinese folk medicine for the treatment of rheumatoid arthritis and asthma. A new neolignan, hancinone (Ⅲ) was isolated together with two known neolignans, kadsurenone (Ⅰ) and denudatin B (Ⅱ). The structure of hancinone (Ⅲ) was established as (7. S, 8 R, 3′S) -1′ - allyl-3′-methoxy-7- (3,4 -methylenedioxyphenyl) - 8 - methyl-7, 8, 3′, 6′-tetrahydro-6′-oxobenzofuran through interpretation of the spectral data (UV, IR, NMR and MS) and the results of a single crystal X-ray analysis.Kadsurenone (Ⅰ) and denudatin B (Ⅱ) were isolated for the first time from this plant.In the PAF receptor binding assay and the test of platelet aggregation, denudatin B (Ⅱ) was substantially less active than kadsurenone (Ⅰ), whereas hancinone (Ⅲ) showed' no PAF antagonistic activity.