Abstract: The construction of new power system needs to adapt to the access of large-scale high-proportion renewable energy,which puts forward higher requirements for the flexibility of system operation. It is urgent to explore and effectively control the idle flexible energy resources. As an efficient way of aggregating distributed energy resources, virtual power plants can provide various flexibility services such as peak shaving, reserving capacity and frequency regulation for the safe operation of new power system.The key technical challenge is how to construct the virtual power plants to fully unlock the adjustable potential of massive distributed energy sources. This paper focuses on the critical issues of operation characteristics, dynamic construction, and trustworthy quantification of flexible energy resources in virtual power plants. It provides a detailed review of the modeling of external characteristics, optimal combination of energy resources, and trustworthy quantification of service capabilities in virtual power plants. Firstly, this paper summarizes the differentiated supporting capabilities of the operation characteristics of flexible energy resources in virtual power plants for their external characteristics and puts forward a general standardized description method. Then, based on the perspective of physics-cyber-social coupling, the key issues and core technologies of dynamic construction and trustworthy quantification of virtual power plants are analyzed respectively, and the coupling relationship from different perspectives and the supporting logic of key technologies from the two dimensions of individual resources and resource clusters are analyzed. Finally, the vital contributions of this paper and the prospects and challenges of virtual power plants serving the new power system are summarized.