As the first step to restore power system swiftly after black-out, black-start has became an important topic in the field of power system research. To provide guidance and reference for the study of power system black-start, the latest research achievements on black-start in China and abroad are summarized, and the research progress on the key technologies of black-start are introduced from five aspects, including selection of black-start power source and unit, planning of black-start route, load recovery, and safety verification. The research prospect is discussed, and it is pointed out that implementation of black-start with power source of clean energy, researches on aided decision making technology, making extended black-start schemes, and focusing on black-start implementations are the future developing trend.