Describe the features of risk for subjects in clinical studies cited the risk manifestations of ethical review：the personnel organization of ethical review boards，and the composition of the ethical review board members.as well as ehical training，follow-up review and ethical regulatory.To avoid these risks，an analysis is made on the causes of ethical review risks，and recommendations are proposed on Strengthen supervision，refom of ethicaI review board setup，greater efforts on training，strengthen field visits，improving mechanism of tracking and acceptance，establishment of an independent data and safety monitoring board.