To study on the phthalides with vasodilating activity of stems and leaves from Ligusticum chuanxiong.The compounds were isolated and purified by MCI,silica gel.etc.Finally,fifteen phthalides were isolated and identified,such as diangeliphthalide A (1),chaxiongnolide D (2),asepoxyligustilide (3),5-hydroxy-3-butylene-phthalide (4),senkyunolide B (5),3-butylidene-7-hydroxyphthalide (6),Z-ligustilide (7),Z-6-hydroxyl-7-methoxyligustilide (8),chuanxiongnolide B (9),levistolide A (10),tokinolideB (11),(3S,3aR)-3-hydroxyethyl-3a,4,5,6-tetrahydrophthalide (12),(3S,3aR,10R)- (-)-10-hydroxyphenylphthalide (13),senkyunolide F (14),neodiligustilide (15).Compounds 1,2,8,12,13 and 15 were firstly isolated from the L. chuanxiong.All tested compounds showed vasodilation in rat thoracic aortic rings.The vasodilation rate of compounds 1,10 and 15 were 65%,73%and 93%at the highest concentrations (12 μM) (P < 0.01),respectively and EC₅₀ were 8.81,8.23,6.2 μM,respectively.In addition,compound 15 (20 μM) significantly inhibited intracellular calcium concentration.The structure-activity analysis showed that hydroxyl substitution had significant effect on the vasodilative activity of phthalides.More importantly,it was found in the activity of compound 1 that enantiomeric (±)>enantiomeric (-)>enantiomeric (+).