The invention belongs to the new compound preparation field, and concretely provides a 2,3-dehydrosilybin derivative, and a preparation method and a use thereof. The structure of the 2,3-dehydrosilybin derivative is represented by general formula I. In the formula I, R1 and R2 are respectively independently selected from H, and C1-6 linear or branched alkyl, cycloalkyl or unsaturated alkyl groups; R1R2N is a morpholino group, a piperidyl group or a pyrryl group; R3, R6, R7 and R8 are respectively independently selected from H, and C1-6 saturated or unsaturated alkyl or acyl groups; R4 and R5 are independently selected from H, C1-6 alkyloxy groups, C1-6 alkyl groups, halogen atoms, a nitro group, C1-6 halogenated alkyl groups, C1-6 alkyl or unsaturated alkyl groups, a hydroxy group, an acyl group, an amino group, an amido group and an ester group; and n is 0, 1, 2 or 3. The invention also provides an application of the 2,3-dehydrosilybin derivative and its pharmaceutically acceptable salts in the preparation of antitumor medicines. The formula I is shown in the specification.