The invention relates to a composition capable of helping control body weight and a preparation method thereof. The composition capable of helping control body weight consists of the following ingredients: 400-500 parts of enzyme-hydrolyzed oat flour, 100-300 parts of milk and milk products, 50-150 parts of plant fat powder, 10-30 parts of medium-chain triglyceride powder, 10-90 parts of soybean protein, 5-30 parts of fruit and vegetable powder, 35-105 parts of resistant dextrin, 10-100 parts of oat bran powder, 10 100-parts of konjac powder, 5-60 parts of a white kidney bean extract, 5-60 parts of collagen pepetides, 3-30 parts of a fiber extract, 5-50 parts of bamboo shoot fiber, 5-15 parts of trehalose, 5-50 parts of rice protein, and 2-20 parts of vitamins and minerals. The compositioncapable of helping control body weight prepared by the preparation method is comprehensive in nutrients, better in weight reduction effects, and capable of effectively controlling body weight.