The invention discloses a baicalin metal complex of which the molecular formula is (C21H17O11) xM (H2O) y, wherein M in the formula is Cu (II), x is 1 and y is 2; or M is Fe (III), x is 2 and y is 0; or M is La (III) or Y (III), x is 3 and y is 0. The preparation method comprises the following steps: adding aqueous alkali into baicalin until the baicalin and alkali (sodium bicarbonate, potassium bicarbonate, sodium formate, potassium formate, sodium acetate, potassium acetate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, sodium phosphate or potassium phosphate) are just completely reacted, then adding metal salt (copper salt, ferric salt, lanthanum salt or yttrium salt) for reaction to obtain the baicalin metal complex. The baicalin metal complex has obviously stronger antibacterial and antitumor activities than the baicalin, can be used for preparing antibacterial drugs and antitumor drugs, and has good development and application prospects. In the preparation method, an organic solvent is not used, a strong basic condition is not adopted, and the method is simple and feasible, is green and environment-friendly and has the advantages of low cost, high product purity and high yield.