Abstract: When a large earthquake occurs, it is highly possible that all of the power supply systems of the nuclear reactor fail, and it is a huge menace for the security of nuclear reactor. In order to enhance the defense in depth of High-Flux Engineering Test Reactor（HFETR）, a removable emergency power supply system（REPSS） is designed as the emergency rescue facilities of HFETR, which is independent of the main power supply system, removable, fast to connect or excide. The paper calculates and analyzes the design capacity of REPSS, and briefly narrates the technical requirements, structure plan and qualification method of anti-seismic diesel generator set of REPSS.