The elderly show the characteristics of aging， comorbidity and physical decline. Due to lack of common medical knowledge，poor communication and poor economic condition or family composition， the elderly patients suffering from the diseases can not have effective communication with the doctors or can not make the medical decision by themselves. This paper explained the ethics significance in medical decision?making， and analyzed the common models of medical decision?making. The paper also explored the status of close relatives’participation in medical decision?making for the elderly at the view of ethic. The necessity of close relatives’ in medical decision?making for the elderly was proposed and the ethical problems in the process were analyzed. The countermeasures and suggestionson of the ethic problems were submitted which is expected to help the elderly patients solve the difficulty， to improve the relationship between the doctors and the patients and to realize the civilization and harmony of the society.