The invention relates to a method for preparing a purification resin for removing arsenic and fluorine in underground water and belongs to the technical field of rein materials. The method comprises the following steps: adding nanometer titania particles into water, uniformly stirring, thereby obtaining titania suspension; adding graphene oxide, acetic acid and chitosan into water, uniformly stirring, dripping the titania suspension, thereby obtaining the mixed particle suspension; adding polyvinyl alcohol and sodium chloride into the mixed particle suspension, thereby obtaining the initial reaction solution; uniformly mixing divinylbenzene, divinyl methylbenzene, methyl methacrylate, propenyl ethanoate and methyl vinyl pyrrolidone, adding a pore-foaming agent, thereby obtaining an organic phase solution; adding the organic phase solution into the initial reaction solution, adding glutaraldehyde and di-tert-butyl dicarbonate ester, heating and reacting, filtering the insoluble substances, cleaning by using water, performing vacuum drying, thereby obtaining the adsorbent.