The invention discloses a method for extracting ruscogenin from ruscus aculeatus, which comprises steps: total saponins is extracted, is absorbed through macroporous resins, is concentrated in a membrane under the conditions that the vacuum degree is 10.7kPa and the temperature is 70-90 DEG C, is hydrolyzed through acids, is extracted through formyl trichloride, is purified through silicagel columns, and is processed through recrystal. The method for extracting the ruscogenin from the ruscus aculeatus is simple and convenient in operation, short in production cycle, high in separation efficiency, steady in process and low in cost, can achieve high purity separation and preparation of industrial ruscus aculeatus sapogenin monomers, achieves the purity of ruscus aculeatus sapogenin monomers above 98%, and is bigger than 85% in recovery rate of effective components.