Threat evaluation to the variety of battlefield situation is one of the key factors in combat decision-making. Combining with the features of actual anti-aircraft combat, analyzing the correlative factors of threat evaluation, a new algorithm of target threat evaluation based on fuzzy judgment rule is given. According to the features of threat targets, different fuzzy relative membership functions are constructed and correlative specifications are quantified. Using fuzzy judgment rule, the model of target threat evaluation is built. A set of example consisting of four targets threat evaluations is given, and the unique threat sequence is calculated as threat assessment basis. The result indicates that the algorithm is effective and feasible.