Abstract: In the past decade, with the implementation of policies to promote the research and development of rare disease drugs, the increase in the number of clinical trials for rare disease drugs has posed new challenges to ethical review. Clinical trials of rare disease drugs involve vulnerable populations with a small number of patients, scattered populations, and relative concentration in certain disease areas. The trials are mainly conducted in the early stages, often requiring small sample sizes, single arm designs, and more new technologies such as cellular and gene therapy. In addition to meeting the general requirements of clinical trials for common diseases, ethical review should also give special attention to the special characteristics of rare diseases in risk benefit assessment, research design, informed consent, trial operation, etc. Ethical review of clinical trials for rare diseases should effectively promote the development of new drugs for rare diseases and protect the rights and interests of participants.By analyzing the characteristics of clinical trials for rare diseases drugs, this paper presents the points of special concern during the review, aiming to improve the level of ethical review for clinical trials of drugs related to rare diseases.