Under the dual-carbon goal, the operation environment and form of the urban power grid have new characteristics, and the urban power grid will be transformed into a new urban power grid (NUPG), which puts forward higher requirements for flexibility. It is urgent to establish a flexible dispatching system to meet the operation of the NUPG. This paper first introduces the eight major new operation characteristics and challenges of the NUPG. Secondly, a flexible dispatching architecture with the load as the main body is constructed, and the types of dispatching objects, dispatching means and media, and internal and external dispatching tasks are introduced. On this basis, four basic dispatching key technologies of the NUPG are pointed out: load response capacity assessment and distribution technology, load reserve configuration and power plan formulation technology, load participation in power grid frequency regulation/peak shaving/voltage regulation technology, and internal and external fault handling technology based on load resources. Finally, the effectiveness of the NUPG dispatching architecture and key technologies is verified by simulation analysis of the IEEE39-bus system and the actual power grid in East China.