The invention discloses a preparation method of a whey protein adhesive specially used for wood, and belongs to the technical field of natural adhesives. The method comprises the following steps: mixing a whey protein, whey proteinase and deionized water, performing constant-temperature ultrasonic enzymolysis, and performing heating for killing enzyme to obtain an enzymatically-decomposed whey protein; performing constant-temperature ultrasonic immersion on bamboo fibers, cellulase and deionized water, performing filtration, and performing drying to obtain pre-treated bamboo fibers; and performing a reaction under heating and stirring on the enzymatically-decomposed whey protein, the pre-treated bamboo fibers, a prepolymerization liquid, modified microcapsules and a surfactant, performingcooling, adding phenolic resin, a mixed enzyme solution and a curing agent, and performing mixing under stirring to obtain the whey protein adhesive specially used for the wood. The whey protein adhesive specially used for the wood provided by the invention has excellent mechanical properties and water resistance.