In the close-range air combat environment with high dynamicity and strong confrontation, the existing situation assessment methods have the problems of insufficient consideration of the indicators related to air combat confrontation characteristic and unreasonable application of constant indicator weights. To address the above problems, this paper proposes a close-range air combat situation assessment based on fuzzy dynamic weight. First, according to the characteristics of close-range air combat confrontation, the influence of missile attack, maneuver characteristics and energy state on air combat situation is explored. The situation assessment indicators system is constructed from multiple perspectives of attack, occupation, maneuver, energy situation and inherent capability, and the corresponding models of assessment indicators are established. Then, a dynamic adaptation method of fuzzy weight based on situation classification is designed. The interval type-2 fuzzy set is applied to represent the uncertainty during the weight determination process, and the fuzzy weights of situation indicators are calculated based on the best-worst method. On this basis, the weight adaptation and indicator aggregation are carried out according to the typical situation styles of the air combat. Finally, the proposed method is validated by experiment and comparative analysis based on air combat flight data. The results show that the proposed method can present the changes of the situation in the process of close-range air combat more reasonably and accurately.