The invention provides a method for extracting total magnolol according to an alcoholic-alkaline method. The method comprises the following steps: firstly drying magnolia bark, smashing the magnolia bark and screening the magnolia bark through a 100 mesh screen, then preparing alcoholic-alkaline solution with 0.01 to 0.025N alkalinity through 50 to 70 percent alcoholic solution, mixing the magnolia bark powder and the alcoholic-alkaline solution according to the ratio of sample to solution (g/ml) being 1:10 to 1:20, performing ultrasonic extraction for 20 to 40 min, performing centrifugal separation, obtaining magnolia bark residue and alcoholic-alkaline solution I containing total magnolol, performing ultrasonic extraction again, concentrating the alcoholic-alkaline solution, adjusting the pH value of the concentrated solution to 2 to 3 through hydrochloric acid, refrigerating the concentrated solution for 6 to 8h at 2 to 6 DEG C, obtaining sediment, washing the sediment through water to be neutral, and the like. The method extracts the total magnolol according to the alcoholic-alkaline method by combining magnolol and physical and chemical properties of the magnolol, and has the advantages that the extraction efficiency is high, the energy consumption is low, the production is reduced, and the method is simple and efficient.