Flexible mutual assistance in resources can be achieved among power grids in different regions，and regions with a high proportion of renewable energy can obtain flexible resources from other regions to ensure the safe and flexible operation of the power grid.Based on this，a cross-regional optimal scheduling method of multivariate flexible resources is proposed considering Stackelberg game.Firstly，the flexible adjustment demand of wind，solar，and other renewable energy and the flexible supply capacity of the typical flexible resources in the source，load，and storage are quantitatively analyzed.An upper-level optimization model for multi-agents within a region is constructed with the goal of minimizing the net benefit of each operator and aggregator.Secondly，the flexible mutual assistance capability of the contact line is analyzed；a lower-level optimal scheduling model for mutual assistance among multi-regional power grids is constructed with the goal of minimizing the operating cost of the power grid in each region；the Stackelberg game is carried out with the upper-level model.Finally，three interconnected IEEE- 39 node systems are constructed for case analysis.The results show that the above-mentioned double-layer optimal scheduling model based on the Stackelberg game can effectively reduce the operating cost of the system and improve the overall flexible mutual assistance level of the power grid.