In view of the existing threat assessment methods commonly used constant weight evaluation, and ignored the problem that the unreasonable situation appeared in evaluation results caused by the target attack signal, an variable weight threat evaluation method considering the target attack signal was put forward. On the basis of hierarchically establishing the target threat evaluation system and the variable weight theory, considering the influence of target attack signal on weight and the relationship between weight and each factor, the variable weight factor was introduced to adjust the weight according to the factors and the actual changes of the battlefield. The simulation results showed that the design method of threat assessment could prevent the occurrence of unreasonable evaluation results, and it was more suitable for the actual battlefied.