The airborne electro-optical sighting devices and seekers of the electro-optical guided weapons are the direct targets of the electro-optical countermeasure system in regional electronic air defence combat. Rapid and accurate target recognition and threat assessment form the basis for command decision-making and effective implementation of jamming. In this paper, the characteristics of the targets in the countermeasure are analyzed firstly. Considering the ambiguous battlefield situation, a target recognition method based on action reasoning is proposed to identify the target type and predict its next action. Finally, a multi-attribute decision-making threat assessment model is established, and used together with the effectiveness reduction analysis, to calculate target threat level. The simulation shows that, this method can make accurate judgment of target attribute and threat level and provide a basis for target assignment in jamming when there is no external intelligence support.