Abstract: Developing nuclear powered spacecraft is the most prospect and reliable technological approach to realize further deep space exploration. However, related development standards for integrated design of nuclear powered spacecraft have not been studied in China . Drwaing lessons from the foreign successful experience of the development of nuclear powered spacecraft, considering the existing standards and specifications as well as the general spacecraft design methods, the key design points were presented for developing nuclear powered spacecraft, including the Top-level Design group for engineering and Top-level Design group for spacecraft. Especially, for the utilization of space nuclear source and the safety protection, the key points and solutions for developing space nuclear source and nuclear safety design are proposed. All of these will be applied to the research and development of nuclear powered spacecraft.