The invention relates to the technical field of medicines, in particular to a method for separating and purifying high-purity monomeric compounds including xanthotoxol, osthenol, oxypeucedanin hydrate, byak-angelicin and imperatorin from angelica dahurica. The traditional methods, such as column chromatography, or recrystallization, and the like, are commonly adopted in China for separating and purifying; high-speed counter-current chromatography is adopted recently for separating and purifying, but separating effect is not ideal. In the method of the invention, firstly, water or ethanol water is used for soaking or preparing a crude extract of the angelica dahurica by refluxing; a macroporous adsorptive resin is firstly adopted to respectively remove water-soluble impurities by water and low-concentration ethanol; the relative high-concentration ethanol is used for eluting; elution liquid is decompressed and concentrated, thus obtaining a macroporous adsorptive resin extract of the angelica dahurica; then a two-dimensional cylinder is adopted to switch and prepare liquid-phase chromatography with high efficiency so as to separate and purify the extract, thus obtaining the xanthotoxol, the osthenol, the oxypeucedanin hydrate, the byak-angelicin and the imperatorin with the purity higher than 99 percent. The method has simple and convenient operation, high separating rate and product purity and is suitable for industrialized production.