A simple, sensitive, and rapid method using gas chromatography (GC)-mass spectrometry (MS) is developed for the simultaneous separation and identification of the active ingredients of Liqusticum Chuanxiong Hort (Chuanxiong). Ten phthalic anhydride derivatives (PADs) are identified in Chuanxiong as 3-butylphthalide, 3-butylidenephthalide, 3-butylidene-4-hydroxyphthalide, senkyunolide A, neocnidilide, Z-ligustilide, E-ligustilide, senkyunolide F, senkyunolide-H, and senkyunolide-I. The existence of ferulic acid and vanillin in Chuanxiong extract is also demonstrated. Further identification of these compounds is performed by thin-layer chromatography, high-performance liquid chromatography (HPLC), and HPLC-MS analysis. This is the first report of the separation and determination of the PADs in Chuanxiong by GC-MS.