The invention relates to a method for rapidly detecting raw stock beer yeast from lower beer yeast. The method comprises the following steps of: firstly pouring a sample to be detected into a YNB-GVBA culture medium with the temperature of 45-50 DEG C, culturing for 2-3 days at the temperature of 36 DEG C, and observing the growth conditions of colonies on the YNB-GVBA culture medium; and if the colonies grow on the YNB-GVBA culture medium and the peripheries of the colonies are changed from green into yellow, the raw stock beer yeast is proved to be mixed into the lower beer yeast. The method for rapidly detecting raw stock beer yeast from lower beer yeast is rapid, convenient and sensitive; simultaneously, the method is applicable to detection of yeast seeding liquid, fermenting liquid and yeast paste of the lower beer yeast; and early discovery, early prevention and early treatment of cross contamination of the beer yeast can be realized only by 2-3 days of the operation time. The implementation of the method does not add extra instrument equipment and does not need special personnel training, so that the applicability is strong.