The present technology generally relates to food-processing industry, namely to a method of processing brewer's grains. The invention enables to increase the level of extracted food fractions of brewer's grains up to 90-95% and to increase protein content in barley protein concentrate up to 50-65% wt (dry solid). The method implies that brewer's grains are subject to loosening by means of a vibrating screen, grinding in a colloid mill with addition of water or centrate in the ratio from 0.5:1 to 1:1 to brewer's grains in order to produce a pasty homogeneous mass from brewer's grains; and then this mass is subject to processing by means of a screw extractor for its further grinding and division into 2 factions: suspension with the humidity level of 90-95%, and ground husk of brewer's grains with the humidity level of 60-75% suitable for its further industrial use. Then the suspension is supplied to mechanical filtration in order to remove the ground husk, pumped into the container and dried in order to obtain the humidity level of max. 7%.