Set in cross-regional interconnected power grid, a coordinated control method based on the multi-agent technology is presented, which is used for blocking power grid transient successive instability, reducing the risk of blackouts and control cost. Based on certain and risk analysis method, it firstly searches the possible transient successive instability modes and fault chains under the action of successive events after system instability caused by severe faults. Then it searches control strategy based on EEAC grouping theory and solves the control strategy contradiction problem with different instability modes. On this basis, it utilizes EEAC quantification analytical tool to sort different control measures. Finally, with the objective of minimizing total system risk preventive control strategy and emergency control strategy are coordinated and optimized. The method is verified by simulation.