Abstract: Ethical review of biomedical research is an important procedure and key point in the construction of ethics governance of science and technology. However, there are problems in the quality of ethical review of biomedical research in China. The core factors which affect the quality of ethical review, include the ignorance of the nature of ethical review being made the moral judgment on the protocol, lack of understanding of the independence of ethical review, the focus of the ethical review being shifted, lack of the capacity of ethical review, the possible conflicts of interest not strictly reviewed, and lack of vigilance at the "ethical dumping". The study of the factors can provide preliminary analysis regarding how to improve the quality of ethical review of biomedical research and promote the mechanism of ethics governance.