Abstract: The present disclosure belongs to the technical field of plant extraction, and particularly relates to mangiferin and a preparation method thereof. The present disclosure includes activated carbon treatment and extraction of raw materials successively to obtain the mangiferin; the raw materials are mango leaves and/or almond leaves; the extraction is absolute methanol extraction, and the extraction is conducted at 60-65° C. Results of examples indicate that mangiferin obtained by the preparation method of mangiferin provided by the present disclosure has a purity of 98% to 99.5%, and mangiferin yield is as high as 66.7% of total mangiferin content in the mango leaves or almond leaves. The preparation method of mangiferin provided by the present disclosure is simple to operate, which obtains high-yield and highly pure mangiferin while reducing production costs of the mangiferin, and realizes the industrial production of the mangiferin.