Preparation method of aloe-emodin

The invention discloses a preparation method of aloe-emodin, which comprises the following steps: firstly, adding aloe cream powder into a 3-6% hydrochloric acid solution, heating at 95-105 DEG C, cooling to room temperature, filtering, washing filter residues with deionized water, and merging filtrate, the corresponding relationship between the mass of the aloe cream powder and the volume of the hydrochloric acid solution being 1: (20-25); the obtained filtrate is heated to 90-100 DEG C, then a triethylamine hydrochloride-ferric chloride ionic liquid is added, heat preservation reflux is performed, after the reaction is finished, filtering is performed, a filter cake is washed with deionized water for 2-3 times until the filtrate does not have obvious color, the filtrate is combined, and the relation between the volume of the triethylamine hydrochloride-ferric chloride ionic liquid and the mass of the aloe cream powder is (2-4.5): 1; and drying the filter cake, and purifying with toluene to obtain the aloe-e