The invention relates to a method for preparing a titanium dioxide layer with a multi-level pore structure on the surface of medicinal titanium. The method provided by the invention comprises the following steps of: performing anode oxidation of a direct-current slow uniform-speed current raising mode on the medicinal titanium in acetic electrolyte, and performing secondary anode oxidation of a direct-current constant voltage mode in sulfuric acid or sodium acetate electrolyte to obtain the titanium dioxide layer with the multi-level pore structure, wherein the large-pore structure consists of staggered groove structures, the widths of grooves are 20 to 30 microns, the small-pore structure comprises submicron micropore structures densely distributed on the whole film, and the aperture is between dozens of and hundreds of microns. The method is simple and rapid, has simple and convenient operation, and is expected to become a surface modification method for medicinal titanium metal in the field of orthopedics, dentistry or plastic surgery.