The invention discloses a health promotion-based pure natural functional drink suitable for diabetic patients to drink. The formula of the drink comprises the following components in parts by weight: 0.5-2 parts of a green tea extract, 0.1-0.5 part of a mate tea extract, 0.1-0.5 part of a guarana extract, 0.05-0.2 part of a panax ginseng extract, 0.05-0.2 part of an acerola cherry extract, 0.05-0.2 part of a rosemary extract, 0.5-2 parts of a natural flavoring agent, 0.5-2 parts of a natural sweetener and the balance of water. The invention further discloses a preparation method of the functional drink. By implementation and long-term drinking of the functional drink by the diabetic patients, the blood sugar can be smooth and tends to be a normal value, thereby being conductive to restoring the diabetic patients to health; and the functional drink can also be drunk by normal people.