OBJECTIVE：To pr ovide reference for improving extended clinical trial system in China. METHODS ：The implementation experience of the international extended clinical trial system was introduced from three aspects ： system development，application scope and principles ，application and approval ；the evolution and challenges of the system in China were further analyzed ，and relative suggestions were put forward. RESULTS & CONCLUSIONS ：The development of international extended clinical trial system in the United States ，the United Kingdom ，Australia and the European Union had been relatively mature. The specific system had not formally been established in China ，and the implementation of the system faced many challenges，such as the ethical problems caused by drug use risk ，the sponsor dilemma caused by the difficult balance between the resistance of initiating application and the benefits ，the difficulty of review caused by the unknown responsible party of risk assessment and the urgent time of approval. It can be dealt with by the following measures ：improving the existing laws and regulations，strengthen information disclosure and risk prevention work ，make clear the division of responsibilities in the process of system operation. Meanwhile ，based on the existing international model ，the management system of the expanded clinical trials in China is established. Corresponding application paths are set up for different application types such as “single patient emergency ”， “single patient non emergency ”and“two or more patients group ”，and all parties should be mobilized to supervise so as to promote the improvement and implementation of the extended clinical trial system.