The invention relates to a pteridium aquilinum, kiwi fruit and siraitia grosvenorii composite grain drink and belongs to the field of food processing. The grain drink is prepared from, by weight, 55-65% of pteridium aquilinum pulp, 12-20% of kiwi fruit juice, 10-13% of a discolored siraitia grosvenorii extracting solution and 10-15% of auxiliary extracting solutions, wherein the auxiliary extracting solutions are aqueous extraction solutions of coix seeds, small red beans and poria cocos. According to the drink, the raw materials are mixed, and the drink is prepared through the steps of homogenization, concentration, granulation, drying and packaging. The drink is a functional instant composite grain drink, is fresh in taste, rich in taste, unique in flavor, moderate in sourness and sweetness, low in calorie and rich and comprehensive in nutrient, has the health-care effects of clearing away heat, moistening the lung, promoting the secretion of saliva or body fluid and performing the moistening function to remove dryness, relieving the sore throat and reducing phlegm, invigorating the stomach and promoting digestion, reducing blood pressure, blood sugar and blood fat and the like while summer heat is relieved and thirst is quenched, conforms to the mind, for homology of medicine and food and analogy of medicine and diet, of most customers, and is particularly suitable for people suffering from hyperlipaemia, phlegm-dampness constitution and obesity to drink.