The invention relates to a method for preparing multi-amino modified cyclodextrin, wherein the method comprises the steps for preparing multi-amino modified cyclodextrin in parts by mass: (1) dispersing cyclodextrin into water, and slowly adding 10%-15% strong alkali aqueous solution into the water until the system is transparent to obtain a solution I; (2) adding p-toluenesulfonyl chloride and acetonitrile into a reactor; dropwise adding the solution I; continuously carrying out a reaction for 3-5 h at room temperature after finishing dropwise adding for 0.5-1 h, ending the reaction, carryingout suction filtration, putting the filtrate into a refrigerator overnight, separating out a large number of white precipitates, carrying out suction filtration to obtain a white solid, dissolving the white solid with water, carrying out suction filtration, refrigerating the filtrate to separate out a large number of white precipitates, filtering, and carrying out vacuum drying to obtain poly-6-p-toluenesulfonyl cyclodextrin; and (3) dissolving the poly-6-p-toluenesulfonyl cyclodextrin and polyamine into a dipole solvent, carrying out a reaction at the temperature of 50-80 DEG C for 4-6 h, adding glycidyl methacrylate, continuing to carry out a reaction for 2-4 h, cooling to room temperature, adding methanol, adding acetone, precipitating, carrying out suction filtration to obtain a whitesolid, and repeating methanol dissolution and acetone precipitation to obtain the double-bond-containing multi-amino modified cyclodextrin.