Ethynyl estradiol in this product is a derivative synthesized from human estrogen estradiol. Estrogen promotes the development, maturation and maintenance of female organs and secondary sexual characteristics through specific binding with estrogen receptors in target tissues and cells, and at the same time has effects on metabolism, cardiovascular system and bones. Medroxyprogesterone acetate is a progestin, which can reduce the occurrence of endometrial cancer by inhibiting the mitosis of endometrial cells, reducing the level of estradiol receptor in endometrial cells and increasing the activities of estradiol dehydrogenase and isoleucine dehydrogenase. When estrogen is used alone, it can make endometrium and mammary duct proliferate, and medroxyprogesterone acetate can inhibit this situation. The incidence of endometrial cancer in menopausal women who use estrogen and progesterone compound preparation is significantly lower than that in menopausal women who do not use it.