The invention discloses a graphene oxide-silk-salix nanocomposite and a preparation method thereof. The preparation method comprises the following steps: modifying salix cellulose by virtue of PAMAM (polyamidoamine); performing freeze-drying treatment to obtain a salix-silk magnetic porous composite by virtue of liquid nitrogen; impregnating the salix-silk magnetic porous composite in an aqueous solution of graphene oxide, taking the salix-silk magnetic porous composite out, repeatedly cleaning the salix-silk magnetic porous composite with ethanol and de-ionized water, and performing vacuum drying to obtain the graphene oxide-silk-salix nanocomposite. According to the graphene oxide-silk-salix nanocomposite and the preparation method thereof, salix and silk are used as substrates, and theraw materials are sufficient and low in cost; then, magnetic nanometer ferriferrous oxide and the graphene oxide are effectively and synergistically self-assembled to obtain the graphene oxide-silk-salix nanocomposite, and the graphene oxide-silk-salix nanocomposite has broad application prospect in the fields of adsorption materials, biological materials and the like.