Two new phthalide dimers, namely chuanxiongnolide A (1) and chuanxiongnolide B (2), along with eleven known phthalides and derivatives ( 3 - 13), were isolated from the roots of Ligusticum chuanxiong Hort. (Umbelliferae). The chemical structures of the new compounds were established by HR-ESI-MS, 1D- and 2D-NMR spectroscopic analysis, whilst the relative stereochemistry of 1 was confirmed by X-ray crystallographic data.