The invention relates to a preparation method of a functional real silk fabric. The method comprises the following steps: carrying out acylation reaction on a real silk fabric, an alkali and an acylating agent under the action of a catalyst to obtain a true silk high-molecular initiator, wherein the acylating agent is alkyl halohydrocarbons; and in a buffer solution with the pH value of 7-8, carrying out graft polymerization reaction on a monomer, the true silk high-molecular initiator and a reducer at 40-80 DEG C to obtain the functional real silk fabric, wherein the graft polymerization reaction is carried out under enzymatic actions, and the monomer is hydroxy acrylate, fluorine-containing acrylate or acrylamide. The true silk high-molecular initiator is firstly prepared, and the enzyme is utilized to catalyze the ATRP (atom transfer radical polymerization) reaction between the monomer and true silk high-molecular initiator surface groups; and by using the enzyme catalyst, the polymerization reaction has the characteristics of environment friendliness, mild reaction conditions and the like.