The invention relates to a preparation method and applications of a photo-thermal and photodynamic co-used antitumor drug delivery system taking gold nano star mediated by folic acid as the carrier. In the prior art, the antitumor drugs have adverse side and toxic effects, moreover, the biocompatibility and targeting performance of the antitumor drugs are bad, and the provided system solves the problems mentioned above. In the preparation method, reaction active amino and carboxylic groups are grafted onto the surface of gold nano stars through covalent bonds, then targeting molecules are connected to the gold nano stars through amidation reactions to obtain a targeting gold nano star solution; then the amino groups on the end of the targeting compounds carry out chemical reactions with near-infrared fluorescence probes so as to obtain a gold nano star solution with functions of folic acid targeting and near-infrared fluorescence imaging; and finally an antitumor drug (adriamycin) is directly loaded on the surfaces of gold nano stars through an electrostatic adsorption effect. The chemical stability and physical stability of the drug delivery system are both very good, the preparation technology is simple, the resources of the raw materials are abundant, the cost is low, the side and toxic effect is little, and the tumor cell proliferation can be effectively inhibited.