In response to the challenge of accurately assessing the threat degree of multiple incoming airborne targets in air defence early warning information systems, an improved TOPSIS aerial target threat assessment method based on game theory is proposed. Firstly, the threat assessment index system and quantitative model are constructed. Then, subjective and objective weights obtained by Analytic Hierarchy Process (AHP) and Entropy Weight Method (EWM) are combined using game theory to obtain the composite weights. Variable weight theory is integrated to improve the combination of constant weights to obtain variable weight weights, so that the indicator weights can be adjusted flexibly with the evolving battlefield situation. Finally, the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) method is enhanced by the Rank Sum Ratio (RSR) method to more accurately achieve target threat ranking and threat level determination. The efficacy of the proposed method is evidenced by a comparative simulation of conventional methods.