The invention belongs to the field of cosmetics and relates to novel application of leech, i.e. application of the leech to nursing of hair or scalp of a head, a composition which is prepared by using the leech as the main raw material and is used for nursing the hair or the scalp of the head, and a preparation method of the composition. For the novel application of the leech, the effects of hirudin on activating blood, dissolving stasis, promoting blood circulation and removing obstruction in channels are utilized for nursing the hair or the scalp of the head, so that blood circulation of the head is strengthened, the blood flow is enhanced, the scalp is nourished, capillary waste of the scalp is removed, melanin is timely conveyed for hair papilla and the hair is blackened and brightened. A research process also shows that the hirudin has capabilities of promoting the metabolism of the scalp, activating hair follicle tissues and strengthening hair roots so as to achieve the effects on hair promotion, hair nourishment and alopecia prevention, fundamentally improve the physiological status of the hair, promote the hair growth and integrate three effects on alopecia prevention, alopecia treatment and hair growth into a whole; and the hirudin also has an effect of repairing damaged hair, so that the hair becomes smooth and tenacious.