Soybean isoflavones are purified natural plant estrogen extracted from traditional soybean. A great deal of studies show that soybean isoflavones play an important role in curing and preventing cancer,heart disease,osteoporosis,relieving women menopause syndrome. In recent years,soybean isoflavones is the hot topic in the researching area of function food. This review introduced researching progresses of soybean isoflavones in its chemical structure, biological properties and physiological function.