The invention relates to a modified starch-based wood adhesive as well as a preparation method and application thereof, which belong to the fields of an adhesive and a preparation method thereof. The preparation method comprises the following steps of: after carrying out acidolysis-gelatinization pretreatment on starch as a main raw material, carrying out graft copolymerization on the starch in aseed emulsion polymerization process by adopting vinyl acetate monomers, and adding nano silicon dioxide sol and other assistants after cooling to finally obtain a wood starch adhesive with excellentperformance. The main technical indexes of the adhesive prepared with the preparation method are all better than those of the traditional starch-based wood adhesive, and the adhesive has the advantages of no toxicity or pollution, high bonding strength, good water resistance, milky white and glossy color, high drying speed, long storage time and the like and can be widely applied to bonding decorative wood and artificial boards.