The trend of bundling regular and new energy has become apparent increasingly in large-scale power transmission base. There is a contradiction between the safety of generator and integrity of grid for multi-generator out-of-step protection. Therefore, multi-generator out-of-step protection action strategy is proposed for large-scale power transmission base considering the safety of both source and grid, maintaining system stability by removing the optimal unit in this paper. By analyzing the causes of multi-generator out-of-step in a large-scale power transmission base, this paper proposes a system stability control strategy under multi-generator out-of-step based on equal area criterion. The optimal cuts number of the system when line faults and loads change suddenly is analyzed and calculated theoretically, improving the stability of the system. Finally, simulation model based on delivery system of multi-unit in parallel verify the minimum cuts strategy proposed in this paper. The effectiveness of the strategy is illustrated by the change of the power angle curve. This work is supported by National Natural Science Foundation of China (No. 51607106) and Research Fund for Excellent Dissertation of China Three Gorges University (No. 2019SSPY050).