“Nuclear emergency” is “the event of a nuclear accident or radiological emergency”, according to IAEA. Civil nuclear emergency system is a part of nuclear safety and the bottom line of the “defense-in-depth” measure, which aimed to act against the nuclear accident to lessen the radioactive harm, protect staff, the public and the environment. Echoed with the development of nuclear power industry in 1980s, Chinese mainland civil nuclear emergency system is paid much attention by the government after the Chernobyl accident in 1986. A great many nuclear experts agree that the system puts more weight on technology, and the framework of management is the centralized embodiment of the system. This study focuses on the development of the Chinese mainland civil nuclear emergency management system, taking a historic view of science and technology. Specifically, it conducted semi-structured interviews with the core participants who established the nuclear emergency management system in the 1980s, including officials, nuclear technology experts and military delegates. The author acquired primary materials, such as work scripts, conference minutes and internal materials and gained a comprehensive understanding of the preparation, establishment and reform of this system. This study draws an outline of the development path and the characteristics of Chinese mainland civil nuclear emergency organization system. This system was formed in a unique circumstance that China is transforming from a planned economy to a more open market economy. On August 21th, 1991, the National Nuclear Emergency Committee announced the" State-Province-Nuclear facilities unit", three levels of civil nuclear emergency organization system, had officially established. With the power of directing and coordinating eighteen ministries and commissions, this committee was affiliated directly under the State Council and led by the Vice Prime Minister. However, as the shadow of major nuclear accidents eliminated gradually, and a one-sided pursuit of economic interests took hold, the strength of nuclear emergency system was weakened. As a consequence, during the national ministerial reform from 1993 to 1995, the executive grade of the National Nuclear Emergency Committee was degraded. Later in 1998，it turned into a subordinate unit of the COSTIND. Therefore, it is a hidden danger that the Committee is powerless to mobilize the national strength in case of a serious nuclear accident.