The invention discloses a medicine for treating hypomenorrhea due to the deficiency of the kidney and a preparation method thereof. The medicine is prepared from the following medicinal raw materials: dried human placenta, eucommia bark, flastem milkvetch seeds, tokay, hairy antlers, sea horses, ursine seal testes and penes, prepared rhizome of adhesive rehmannias, dried longan pulp, cochinchinese asparagus roots, noble dendrobium stems, manyflower solomonseal rhizomes, barbary wolfberry fruits, glossy privet fruit, tortoise shells, rose flowers, gaulis aristolochiae, Danshen roots, twotooth achyranthes roots, suberect spatholobus stems, goat or sheep testes, dragonflies, Elaphurus Davidianus Milne-Edwards, greywhitehair raspberry fruits, air bladders of yellow croakers, freshwater sponge, wild groundnut seeds, cushaw stems, dahurian rose fruits and ford metalleaf roots. The medicine has the functions of nourishing the kidney, strengthening the essence, nourishing blood and regulating menstruation and is mainly used for treating hypomenorrhea due to the deficiency of the kidney. The medicine is prepared by integrating the concept of wholism with the treatment based on syndrome differentiation, can be used for improving the overall function, state and immunity of the human body, regulating qi and blood and improving the metabolism of blood, is targeted at hypomenorrhea due to the deficiency of the kidney, can take effect on the diseased part directly, is short in course of treatment, causes less adverse reactions, is safe and efficient, can be used selectively according to different clinical symptoms, can be applied conveniently and can be easily accepted by patients, and patients can not become resistant to the medicine.