Abstract: The increase in renewable energy and load types brings greater uncertainty to the operation of the power system, as well as challenges to the economic dispatch of the power system. Deeply analyzing and summarizing the characteristics of flexible resources and accurately modeling uncertainty are the basis for evaluating the flexibility of power systems and achieving economic dispatch. Model or data-driven based scheduling modeling methods face many challenges, and combining model and data-driven approaches and fully leveraging their advantages is the development direction of power system optimization scheduling. We summarize and organize from following three aspects: flexible resource classification and characteristics, system flexibility evaluation methods, and optimization scheduling models and data-driven modeling. Firstly, the flexible resources in the system were introduced from three aspects: grid side, supply side, and demand side, and their regulation characteristics were summarized. Secondly, three commonly used power system flexibility evaluation indicators, namely, weight allocation, mathematical statistics and envelope interval, were introduced, and the applicability of different methods was summarized. Then, current research status of flexible resource allocation driven by model driven, data driven, and model-data interac-tion driven was summarized. Finally, the prospects in research of power system flexibility are put forward.