Multi-platform formation cooperative operation has become an important style of modern air combat. Through the formation cooperative assessment of air target threats, the offensive and defensive resources in the formation can be more effectively and reasonably scheduled, and the comprehensive combat efficiency of the formation can be improved. Due to the high real-time and dynamic characteristics of the modern air combat environment, there is great uncertainty in the air threat faced by the formation. How to form an organic whole of the formation’s cooperative accusation, electromagnetic management, and fire attack has become a key problem to be solved urgently. Considering target characteristics, battlefield situation and offensive and defensive means, the TOPSIS method based on the nonlinear two-level decision is used to establish a target threat assessment model in formation cooperative combat, and the effectiveness of the model is verified by example simulation.