The invention belongs to the technical field of food processing, and particularly relates to health care oatmeal with a function of loosing weight, and a preparation method of the health care oatmeal. The health care oatmeal is prepared by the following raw materials: oatmeal, Chinese wampee fruits, rhodomyrtus tomentosa, mulberries, lotus leaves, herba lycopi and xylitol. The health care oatmeal with the function of loosing weight is prepared by combining the effective extraction components of natural fruits and plant extract components with effect of homology of medicine and food, thus having the effects of loosing weight, lubricating the intestines, relaxing the bowels, helping digestion, inhibiting appetite, removing fat and reducing blood pressure, balancing nutrition, beautifying and protecting skin, and the like; the health care oatmeal also has the characteristics that the raw materials are easily available, the operation is simple, the flavor is unique, the taste is good, the taking is convenient, etc.