Abstract: Power system transformation is the inevitable need of energy revolution. Power system plays a key role in ensuring the realization of the core indicators of energy transformation. Therefore, a new generation of power system must be built. The flexibility of power system is the remarkable feature of future power system, which has been widely recognized by scholars at home and abroad. The demand for flexibility in three links of "source-network-load" of power system is analyzed at the technical level, and the key technologies of flexibility in new generation of power system are identified concisely. The development of these key technologies is briefly described and prospected. The results show that, through a large number of flexible technology researches and construction of related projects, the innovation, coordination, green, open and shared development of the power system itself will be greatly promoted, and the energy revolution will be further promoted.