Preparation method of tetrahydroxyxanthone and bellidifolin

The invention discloses a preparation method of tetrahydroxyxanthone and bellidifolin. The preparation method comprises the following steps: (1) providing one or more of centaurea solstisiualis, radixthalictri simplicis, swertia bimaculata, and gentianella acuta, using an alcohol solution to carry out heating reflux extractions, merging extracts (A), and carrying out concentration to obtain a concentrated solution (B); (2) extracting and concentrating the concentrated solution (B) to obtain an extract (C); (3) subjecting the extract (C) to column chromatography separation, using a dichloromethane-methanol system to carry out gradient elution, collecting the solution (D), when the column ratio of dichloromethane to methanol becomes from 100:0 to 40:1, and collecting the solution (E), whenthe column ratio of dichloromethane to methanol becomes from 40:1 to 10:1; and (4) concentrating the solution (D) to obtain an extract (H), re-crystallizing the extract (H) to obtain a product (I), drying the product (I) in va