The invention discloses a method for preparing a mixed photonic crystal composite material based on folic acid modification. Silica gel colloid microspheres are used as a template and are placed in areaction tube, a pre-gel A is added, reaction and polymerization are performed, the silica colloidal microspheres are removed, and an invers-opal skeleton is prepared; a pre-gel B is added to the skeleton, reaction and polymerization are preformed for 20-60 s, and mixed photonic crystals are prepared; followed by, a folic acid-dimethyl sulfoxide mixed solution is prepared, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride is added, the mixed photonic crystals reacts with N-hydroxysuccinimide, then the product is washed, and the composite material is prepared. The method has the remarkable advantages of simple and easy preparation method and low equipment requirements; the prepared composite material has strong stability, has excellent biocompatibility and magnetic responsiveness,can specially, sensitively, simply and effectively capture myelogenous leukemia drug-resistant cells, and allows drug-resistant cell strains to have good biological activity.