The invention belongs to the field of food, and in particular relates to a composition with an effect of preventing alopecia and a preparation method thereof. The composition consists of a preparation for oral administration and a preparation for external application, wherein the preparation for oral administration is prepared from the following components: notoginsenoside, dodder extract, mulberry bark extract, medium-chain fatty acid glyceride, phospholipid, vitamin E and rapeseed oil; and the preparation for external application is prepared from the following components: peppermint oil, notoginsenoside, safflower extract, ginger extract, ethanol and water. The composition achieves the purposes of preventing and/or treating alopecia through inhibiting male hormone, strengthening functions of the hair follicles, moisturizing the scalp, inhibiting the activity of 5-alpha reductase and improving sebum secretion.