The invention discloses a formula of banana milk and a preparation method thereof. Each 1000L of banana milk comprises the following raw materials in parts by weight: 20-100kg of bananas, 30-70kg of milk powder, 45-80kg of white granulated sugar, 100-200kg of water, 10-50kg of crystalline fructose, 3-10g of glycerin monostearate, 10-20g of sucrose fatty acid ester, 5-15g of sodium tripolyphosphate, 15-20g of carrageenan, 5-10g of guar gum, 2-10g of trisodium phosphate and 0.1-1g of edible essence. According to the formula and the preparation method, many white-collar workers who are in fast pace state for a long time and expose before computers for a long time and undergraduates are disturbed by the problems of gastrointestinal diseases, skin diseases, constipation, haemorrhoids and the like caused by irregular diet, unhealthy sitting postures and long-term shortage of exercises, so that the new matching of banana and milk is beneficial to digestion for the white-collar workers and the undergraduates. The banana milk is capable of preventing constipation, and curing laryngopathy, anemia and the like.