The invention provides a method for extracting anthocyanins from a butterfly pea. The method for extracting anthocyanins from the butterfly pea comprises the steps that (1) refluxing and degreasing are carried out on the butterfly pea with an organic solvent, and the organic solvent is recovered under reduced pressure; (2) the degreased butterfly pea is placed in acid cold water for extraction, and extract liquid is centrifuged to obtain a clear solution; (3) the clear solution is filtered by an ultrafiltration membrane to collect permeate; (4) the permeate is subjected to reverse osmosis membrane concentration to obtain a concentrate solution; (5) ethanol is added to the concentrate solution, a mixture is refrigerated and centrifuged, and a clear solution is obtained; (6) the clear solution is diluted and then adsorbed by macroporous resin; (7) the clear solution is eluted with the gradient ethanol containing natural antioxidants, and a stripping solution is separately collected; and(8) the stripping solution is concentrated and dried to obtain the anthocyanin product. The various content of the anthocyanin products can be simultaneously extracted from the butterfly pea, and theanthocyanin product content is high; and the whole extraction process condition is mild, and the method for extracting anthocyanins from the butterfly pea has the characteristics such as high yield and environmental friendliness.