Abstract: Provided are a composition for the ketogenic diet and a preparation method thereof, specifically a composition suitable for the ketogenic diet provided in a liquid form, which has the ketogenic ratio of 3-5:1, and a preparation method thereof. The composition for the ketogenic diet according to the preparation method of the present invention can be easily taken by patients since it does not cause rejections such as vomit or diarrhea which may occur with the start of the ketogenic diet, and eliminate the inconvenience of taking additional food for obtaining other functional elements required for the human body owing to functional substances included therein. Moreover, the homogenous liquid form of the present composition allows it to easily slide down the throat and provides good texture in the mouth, thereby it helps a patient to easily take the same.