The invention discloses an extraction method of defatted wheat germ protein. The extraction method includes crushing low-temperature defatted wheat germs to make even wheat germ slurry, using an ultrasonic vibration classifying screen for wet screening, subjecting screening product to centrifugal settling separation and acid precipitation to obtain protein precipitate, and subjecting the protein precipitate to washing, modifying, sterilizing and drying to obtain the finished wheat germ protein. Compared with the prior art, the extraction method has the advantages that screening efficiency is high, meshes are less easy to block, power consumption is low and the like. By the extraction method, protein dissolution quantity can be increased, protein purity and yield can be increased, the protein is fine in dispersiblity, emulsibility, foamability, water retention and oil retention, the primary concentration of the protein can be achieved, and wheat germ dietary fiber, high-added-value product, can further be obtained from oversize product, and accordingly comprehensive utilization rate of the wheat germs is increased. In addition, the extraction method has low requirement for production equipment, is simple in process sequence and is convenient for industrial popularization.