The chapter mainly introduces the development background and international development status of SSP. Energy crisis and global climate change are major issues that affect global sustainable development. Developing clean energy, exploiting renewable energy, gradually replacing traditional fossil energy and achieving net zero emissions as soon as possible have become the global consensus. Aerospace technology, as a cutting-edge technology field, can provide strong support for solving global warming problems. Compared to using solar energy on the ground, using solar energy in space has very prominent advantages. Space solar power can provide massive, continuous, stable, clean and green electricity, and may become an important part of the clean energy. With the improvement of reusable launch technology and the ability to develop large-scale spacecraft, developing SSP is gradually becoming of great practical significance from the technical and economic perspective. The value of SSP has been being re-emphasized by the United States, Japan, China, ESA (European Space Agency), South Korea, the UK, Australia, related international organizations and private companies. They regard SSP as an important policy option to meet this challenge. The next 10–20 years will be the important period for rapidly technological breakthroughs, on-orbit demonstration, and application. SSP is facing new development opportunities.