Abstract: The rapidly increasing proportion of volatile energy generation represented by wind power and photovoltaic power puts forward higher requirements for operational flexibility of a power system. In this paper, considering the volatility, uncertainty and correlation of wind power and photovoltaic power, the fluctuation domain of the multiple random sources is described by multidimensional envelopes, and the system flexibility requirement quantitative model is constructed. The spatial distribution characteristics of the flexibility requirements are obtained by projecting the multidimensional envelopes on the transmission line. Aiming at the optimal scheduling problem considering flexibility requirements, an interval optimal rolling scheduling model considering the spatial distribution constraints of flexibility demands is established, obtaining a generation scheduling scheme satisfying the flexibility requirements under a given confidence level. Finally, the effectiveness of the quantitative method of flexibility requirements and the dispatching method is verified by simulation on the IEEE 39-bus system and the Northwest China grid.